Re: Parafocussing definition?

[Lubomir Smrcok]

OK,
why not to go to Oxford dictionary and consider Greek origin od the word ?
If doing so one finds :

1.1Beyond or distinct from, but analogous to:

and there's, IMHO, the point.

Best,
Lubo


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++

a request to Russia

[Lubomir Smrcok]

May I ask our Russian colleagues if anybody could provide me with a copy 
of a little bit older paper by Pinsker :


Kristallografiya 1966 11 741 748

There's no need for  English version, thanks.

Best regards,
Lubo


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Re: structure solution terminology

[Lubomir Smrcok]

Perfect ! But fancy a sentence in your future paper : Crystal structure 
was solved by other method. 
lubo


On Thu, 17 Dec 2015, A. van der Lee wrote:


According to the IUCr it should be named 'other'.
See here:

cif tag 'atom_sites_solution_primary'
<http://www.iucr.org/__data/iucr/cifdic_html/1/cif_core.dic/Iatom_sites_solution_primary.html>

best wishes, Arie




On Thu, 17 Dec 2015, Leonid Solovyov wrote:


What's the right nickname for the method of structure solution from
powders


In Russian we use an equivalent to 'structure decipher'.
Sometimes, however, this is really 'structure solution' when we apply
vodka in the process ;)

***
Leonid A. Solovyov
Institute of Chemistry and Chemical Technology
660036, Akademgorodok 50/24, Krasnoyarsk, Russia
http://sites.google.com/site/solovyovleonid
***


On Thu, 12/17/15, Lubomir Smrcok <uachs...@savba.sk> wrote:

Subject: structure solution terminology
To: rietveld_l@ill.fr
Date: Thursday, December 17, 2015, 5:05 AM

Hi,

I feel I have a problem with terminology. What's the right
nickname for
the method of structure solution from powders, which instead
of analyzing
electron (nuclear) density shuffles atoms or molecules
around a cell and
compares experimental and calculated patterns ? It could be
well used also
for single crystal data, I know, but it is not routinely
done (yet ?).

I remember that colloquially used phrase "structure solution
in direct
space" woke me up several times during plenary lectures at
several
conferences. What are we having in direct space ? IMHO just
electron
(nuclear) density. Its FT is our diffractogram so that if we
fit
diffractogram, are we still in direct space ? Of course,
reciprocal space
is a pure math and diffracted beam is quite realistic (BTW,
are
there photons also in reciprocal space :-) ?). But in which
space are we when doing any
crystallographic calculation ? OK, OK, you know what I am
asking ... no
bad jokes, please.

May I ask for your 2 cents ?
Thanks,
Lubo




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--
**
A. van der Lee
Institut Européen des Membranes
CNRS - UMR 5635
Université de Montpellier II - Case Courrier 047
Place E. Bataillon
34095 MONTPELLIER Cedex 5 - FRANCE

Tel : 33 (0) 4 67 14 91 35
Fax : 33 (0) 4 67 14 91 19

**
member of RECIPROCS - Réseau des Enseignants, Chercheurs et ITA
Professionnels de la Cristallographie Structurale (French professional
crystallographer network):
http://metiersit.dsi.cnrs.fr/index.php?page=ReseauMetiers=B
**
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++

RE: structure solution terminology

[Lubomir Smrcok]

In fact, one could agree with you. The problem is that RMC name has 
already been reserved, maybe even patented  :-)

Best wishes,
Lubo


On Thu, 17 Dec 2015, Mike Glazer wrote:


But the original question was:
What's the right nickname for the method of structure solution from powders, 
which instead of analyzing electron (nuclear) density shuffles atoms or 
molecules around a cell and compares experimental and calculated patterns ?
That's what we do with RMC in practice. We use RMC to create models and then 
compare with experimental patterns.
Mike

Professor A M Glazer
Department of Physics
Parks Road
Oxford
OX1 3PU
United Kingdom
Tel/Fax: 44 1865 272290
Mobile: 0778 696 0537
**
Vice-President of the International Union of Crystallography
Emeritus Professor of Physics and
Emeritus  Fellow of Jesus College Oxford
Visiting Professor at the University of Warwick
Crystallographer
**
" Je ne te parlerai que cristaux" L. Pasteur (1850) 



http://ukcatalogue.oup.com/product/9780198744306.do


-Original Message-
From: Radovan Cerny [mailto:radovan.ce...@unige.ch]
Sent: 17 December 2015 11:03
To: Mike Glazer <mike.gla...@physics.ox.ac.uk>; Lubomir Smrcok <uachs...@savba.sk>; 
Leonid Solovyov <l_solov...@yahoo.com>
Cc: rietveld_l@ill.fr
Subject: RE: structure solution terminology

RMC covers only a part of the "Direct space methods", not for example methods 
using evolution algorithms.


Radovan Cerny
Laboratoire de Cristallographie, DQMP
Universit? de Gen?ve
24, quai Ernest-Ansermet
CH-1211 Geneva 4, Switzerland
Phone  : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08 mailto : 
radovan.ce...@unige.ch
URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm


-Message d'origine-
De : rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] De la part de 
Mike Glazer Envoy? : jeudi 17 d?cembre 2015 11:49 ? : Lubomir Smrcok; Leonid 
Solovyov Cc : rietveld_l@ill.fr Objet : RE: structure solution terminology

This all sounds like Reverse MonteCarlo (RMC) modelling. We have used this with 
PDF analysis.
Mike Glazer


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++

Re: structure solution terminology

[Lubomir Smrcok]

Sorry,

Arie, genetic algorithm (or its relatives) does not shuffle electron 
density, just atom coordinates. Taking them the procedure (not GA itself) 
calculates structure factors and compares them to the "observed" structure 
factors (their squares, or intensities). Decision making process of GA is 
not based on the differences in electron density, but on |Fo|^2-|Fc|^2.


Lubo


On Thu, 17 Dec 2015, A. van der Lee wrote:


I agree with Yaroslav Filinchuk's thoughts:

"However, the "structure solution in direct space" does not attempt to
work in the reciprocal space - all the manipulations are done in the
direct space."

RMC, normal MC, genetic algorithms, they all shuffle electron density in some 
or another way in real space. So 'real space structure solution' sounds the 
best, and 'real space' is better than 'direct space' as to avoid confusion 
with 'direct methods'.


Arie
ps: we should propose a new possible data value for 
_atom_sites_solution_primary
By the way the data value vecmap (real-space vector search) is, I suppose, 
equivalent to a real-space Patterson search, which is indeed not the same as 
RMC, normal MC, genetic algorithms or other shuffle methods.



Mike Glazer wrote the following on 17/12/2015 12:50:

But the original question was:
What's the right nickname for the method of structure solution from 
powders, which instead of analyzing electron (nuclear) density shuffles 
atoms or molecules around a cell and compares experimental and calculated 
patterns ?
That's what we do with RMC in practice. We use RMC to create models and 
then compare with experimental patterns.

Mike

Professor A M Glazer
Department of Physics
Parks Road
Oxford
OX1 3PU
United Kingdom
Tel/Fax: 44 1865 272290
Mobile: 0778 696 0537
**
Vice-President of the International Union of Crystallography
Emeritus Professor of Physics and
Emeritus  Fellow of Jesus College Oxford
Visiting Professor at the University of Warwick
Crystallographer
**
" Je ne te parlerai que cristaux" L. Pasteur (1850)


http://ukcatalogue.oup.com/product/9780198744306.do


-Original Message-
From: Radovan Cerny [mailto:radovan.ce...@unige.ch]
Sent: 17 December 2015 11:03
To: Mike Glazer <mike.gla...@physics.ox.ac.uk>; Lubomir Smrcok 
<uachs...@savba.sk>; Leonid Solovyov <l_solov...@yahoo.com>

Cc: rietveld_l@ill.fr
Subject: RE: structure solution terminology

RMC covers only a part of the "Direct space methods", not for example 
methods using evolution algorithms.



Radovan Cerny
Laboratoire de Cristallographie, DQMP
Universit? de Gen?ve
24, quai Ernest-Ansermet
CH-1211 Geneva 4, Switzerland
Phone  : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08 mailto : 
radovan.ce...@unige.ch

URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm


-Message d'origine-
De : rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] De la 
part de Mike Glazer Envoy? : jeudi 17 d?cembre 2015 11:49 ? : Lubomir 
Smrcok; Leonid Solovyov Cc : rietveld_l@ill.fr Objet : RE: structure 
solution terminology


This all sounds like Reverse MonteCarlo (RMC) modelling. We have used this 
with PDF analysis.

Mike Glazer



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--
**
A. van der Lee
Institut Europ?en des Membranes
CNRS - UMR 5635
Universit? de Montpellier II - Case Courrier 047
Place E. Bataillon
34095 MONTPELLIER Cedex 5 - FRANCE

Tel : 33 (0) 4 67 14 91 35
Fax : 33 (0) 4 67 14 91 19

**
member of RECIPROCS - R?seau des Enseignants, Chercheurs et ITA
Professionnels de la Cristallographie Structurale (French professional
crystallographer network):
http://metiersit.dsi.cnrs.fr/index.php?page=ReseauMetiers=B
**

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++

structure solution terminology

[Lubomir Smrcok]

Hi,

I feel I have a problem with terminology. What's the right nickname for 
the method of structure solution from powders, which instead of analyzing 
electron (nuclear) density shuffles atoms or molecules around a cell and 
compares experimental and calculated patterns ? It could be well used also 
for single crystal data, I know, but it is not routinely done (yet ?).


I remember that colloquially used phrase "structure solution in direct 
space" woke me up several times during plenary lectures at several 
conferences. What are we having in direct space ? IMHO just electron 
(nuclear) density. Its FT is our diffractogram so that if we fit 
diffractogram, are we still in direct space ? Of course, reciprocal space 
is a pure math and diffracted beam is quite realistic (BTW, are 
there photons also in reciprocal space :-) ?). But in which space are we when doing any 
crystallographic calculation ? OK, OK, you know what I am asking ... no 
bad jokes, please.


May I ask for your 2 cents ?
Thanks,
Lubo

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++

Re: structure solution terminology

[Lubomir Smrcok]

OK,
But I am sure that any deciphering is a systematic rather than a random 
process. I can however agree that when such a systematic process is fueled 
by drinks, some random mental leaps might play a role.
This fact, unfortunately, does not help in solving this terminology 
problem - at least not here.

Regards,
Lubo


On Thu, 17 Dec 2015, Leonid Solovyov wrote:


What's the right nickname for the method of structure solution from powders


In Russian we use an equivalent to 'structure decipher'.
Sometimes, however, this is really 'structure solution' when we apply vodka in 
the process ;)

***
Leonid A. Solovyov
Institute of Chemistry and Chemical Technology
660036, Akademgorodok 50/24, Krasnoyarsk, Russia
http://sites.google.com/site/solovyovleonid
***


On Thu, 12/17/15, Lubomir Smrcok <uachs...@savba.sk> wrote:

Subject: structure solution terminology
To: rietveld_l@ill.fr
Date: Thursday, December 17, 2015, 5:05 AM

Hi,

I feel I have a problem with terminology. What's the right
nickname for
the method of structure solution from powders, which instead
of analyzing
electron (nuclear) density shuffles atoms or molecules
around a cell and
compares experimental and calculated patterns ? It could be
well used also
for single crystal data, I know, but it is not routinely
done (yet ?).

I remember that colloquially used phrase "structure solution
in direct
space" woke me up several times during plenary lectures at
several
conferences. What are we having in direct space ? IMHO just
electron
(nuclear) density. Its FT is our diffractogram so that if we
fit
diffractogram, are we still in direct space ? Of course,
reciprocal space
is a pure math and diffracted beam is quite realistic (BTW,
are
there photons also in reciprocal space :-) ?). But in which
space are we when doing any
crystallographic calculation ? OK, OK, you know what I am
asking ... no
bad jokes, please.

May I ask for your 2 cents ?
Thanks,
Lubo

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++

ortep

[Lubomir Smrcok]

Hi,
Could anybody donate a PDF/PS version of the original manual of Ortep ? 
The page Uncle Google leads to, 
http://web.ornl.gov/sci/ortep/man_pdf.html, seems to give links to 
the non-existing ftp server.

Thanks.

Best wishes,
Lubo

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++

a natural sample

[Lubomir Smrcok]

Hello everybody,
May I ask mineralogist  geologists reading this mails (especially 
European) if anybody could help us in obtaining of an amount of 
well-ordered 
mineral, montmorillonite, nick-named Mikhlailov from Bulgaria ? My 
apologies for posting it here, by all my 
attempts to make a contact to those few mineralogists I could know there 
have all failed.
Thanks for reading this non-Rietveld mail, but this is the only group I 
contribute.

Best,
Lubo

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++

Re: Peak assymtery not able to fit

[Lubomir Smrcok]

Well,
I do not work with metals and therefore my question could be somehow 
naive. 
Suppose you have such funny peaks and you are sure it is not due to 
experimental conditions. How unique is than  the interpretation offered by 
Leonid ? Nothing presonal, of course :-)

lubo




On Mon, 15 Jun 2015, Leonid Solovyov wrote:


Dear Apu,

As the 2nd peak seems to be broader than the 1st one, the broadening is most 
probably due to the stacking faults, typical for the close-packed metals. The 
asymmetry and complexity of the broadening might also suggest the presence of 
crystallites with different degree of faulting (and/or size). Among DDM ( 
http://sites.google.com/site/ddmsuite ) examples there is a model for Cu ( 
\DDM195d\EXAMPLES\Defects\Cu.ddm ), accounting for the influence of faults on 
both peak broadening and intensities. It may also be applicable to Ni, but in 
this particular case a two-phase model might be necessary to allow for the 
presence of different crystalline fractions.

Best regards,
Leonid

***
Leonid A. Solovyov
Institute of Chemistry and Chemical Technology
660036, Akademgorodok 50/24, Krasnoyarsk, Russia
http://sites.google.com/site/solovyovleonid
***



From: Apu Sarkar apusar...@gmail.com
To: rietveld_l@ill.fr rietveld_l@ill.fr
Sent: Monday, June 15, 2015 12:59 PM
Subject: Peak assymtery not able to fit



Hi,

I am working on a nanocrystalline Nickel sample. I am not able to fit the peaks 
to get FWHM and Integral Breadth.

Please see the attached images. Fig. 1 shows the profile and a zoomed view of a 
peak. Tail part of the peak is broader.

Fig. 2 shows the winplotr fit. It is not matching the max intensity.

Please give you suggestions to get a better fit for this kind of XRD peak.


Thanks
Apu

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RE: Powder Diffraction Discussion Group on Facebook

[Lubomir Smrcok]

 scientists in the
Rietveld List. And I foresee many links in Facebook to the
rietveld_list_archives for everyone to use this accumulated knowledge,
while Mark Zuckerberg tries to sell them X-ray instruments, or X-files DVDs
or X-plane tickets or whatever the automatic software that drops
advertisement in our screen understands of what we talk about...

With best regards,

Leo

* List of important labs and universities I found in Facebook in 1 minute
search:

https://www.facebook.com/iucr.org?fref=ts

https://www.facebook.com/cnrs.fr?fref=ts

https://www.facebook.com/pages/Institut-Laue-Langevin-ILL/148452651846298?f
ref=ts

https://www.facebook.com/pages/DESY/103119693061304?fref=ts

https://www.facebook.com/MITnews?fref=ts

https://www.facebook.com/imperialcollegelondon?fref=ts

need more?

 --

Enviado desde mi m?vil.
Prof. Dr. Leopoldo Suescun
Cryssmat-Lab/DETEMA,  Facultad de Qu?mica,  Universidad de la Rep?blica, 
Montevideo,  Uruguay.


El jun 9, 2015 4:15 AM, Radovan Cerny radovan.ce...@unige.ch escribi?:

Too many channels = crystallographer's death (freely translated from an old
proverb Too many hunters= rabbit's death).

Rather to express my opinion that if you have too many options where to look
for an info, you spend too much time before you find it.
Why the troglodytes should learn Facebook? Why do not the younger and more
up-to-date researcher use the email?


Radovan Cerny
Laboratoire de Cristallographie, DQMP
Universit? de Gen?ve
24, quai Ernest-Ansermet
CH-1211 Geneva 4, Switzerland
Phone  : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08
mailto : radovan.ce...@unige.ch
URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm


-Message d'origine-
De : rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] De la part
de LUIS MARIA RODRIGUEZ LORENZO
Envoy? : mardi 9 juin 2015 08:15
? : rietveld_l@ill.fr
Objet : Re: Powder Diffraction Discussion Group on Facebook



hehe, well played Lubo. People can define themselves as they wish, the
problem is the impression we produce in others with our self-definitions.
still the more channels people have to reach information , the best, and as
someone says before, if it does not work it will fade out with no damage.


Quoting Lubomir Smrcok uachs...@savba.sk:

 Dear Luis,

 I always find weird and sort of funny when someone cannot accept that
 some people could call themselves troglodites meaning that they are
 not very enthusiastic about ALL what other people call new and
 progressive or even an innovation. This is how I understand Larry's
 comment.

 Personally, though I am younger than him I do not feel like a
 second-rate human being or depleted of any important scientific
 information when I completely ignore facebook and its clones. This way
 of communication or, better, its information contents, strongly
 resembles that described in Brave New World by A.Huxley. Though
 published in 1932, it has been somehow ahead of the times.

 A word of warning for facebookers : be careful, this is a book (check
 the word with any good on-line service).  Fortunately, it is offered
 also for Kindle so no worry for being seen with a pretty thick piece
 of paper.

 Best,
 Lubo




 On Tue, 9 Jun 2015, LUIS MARIA RODRIGUEZ LORENZO wrote:


 Dear all,

 Although not an active player on this list, except maybe in my early
 days in late 90,s,(science , took me in a different
 direction) I still keep track of what is happening in the Refinement
 world and i would like to add my thoughts on this non technical
 matter.
 The generation of people called millennials  and young scientists
 among them, get inform through facebook and similar. That link them
 to several sources of information without attaching them to one
 single source .

 A facebook page related and linked to this discussion group could be
 the gate to new researchers (students) to this page and have a
 positive influence on the size of this community and their access to
 the very specific questions and knowledge that are usually discussed
 here. Their alternative can be the use of the potent available
 software to have results without guidance (e.g after , no sensible
 responses have been obtained through linkedyn or research gate, to
 name some, because nobody with the right expertise is there). It does
 not have to be a different or parallel discussion group, and it does
 not imply that you have to join  or use any new group. it is most
 likely to have a positive effect or maybe just null in the worst
 scenario.

 In a more personal opinion , i always find weird and sort of funny,
 when people, whose work is to develop and spread knowledge, is proud
 to be a troglodite and do not dare to experience innovation.
 Facebook does not change  the way Science should be done but it may
 change the way of communicating .

 Please dont take offence for my last comment , that is out of my purpose.
 Best regards
 Luis



 Quoting Reinhard Kleeberg kleeb...@mineral.tu-freiberg.de:

 To be honest, I

RE: Powder Diffraction Discussion Group on Facebook

[Lubomir Smrcok]

But not through Rietved_l as Allan has forbidden attachments :-)
lubo


On Thu, 11 Jun 2015, Cline, James Dr. wrote:


I'll send you a copy of the selfie...


James P. Cline
Materials Measurement Science Division  
National Institute of Standards and Technology
100 Bureau Dr. stop 8520 [ B113 / Bldg 217 ]
Gaithersburg, MD 20899-8523    USA
jcl...@nist.gov
(301) 975 5793
FAX (301) 975 5334

-Original Message-
From: Lubomir Smrcok [mailto:uachs...@savba.sk]
Sent: Thursday, June 11, 2015 1:30 PM
To: Cline, James Dr.
Cc: rietveld_l@ill.fr
Subject: RE: Powder Diffraction Discussion Group on Facebook

Well,
Strictly speaking, you are wasting your time in (formally) two different ways 
:-) And you shouldn't forget to tweet about it and to take a selfie while 
typing.
Lubo


On Thu, 11 Jun 2015, Cline, James Dr. wrote:



Not a great deal of difference between these entities, IMHO.



Jim





James P. Cline
Materials Measurement Science Division National Institute of Standards
and Technology
100 Bureau Dr. stop 8520 [ B113 / Bldg 217 ]
Gaithersburg, MD 20899-8523USA
jcl...@nist.gov
(301) 975 5793
FAX (301) 975 5334



From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On
Behalf Of Darren Broom
Sent: Thursday, June 11, 2015 11:17 AM
To: Young Lindsay Kay; rietveld_l@ill.fr
Subject: Re: Powder Diffraction Discussion Group on Facebook



On a related note, with regard to accessing Facebook at work, I
generally only use it to keep in touch with friends; and I try to
avoid mixing the two. I'm sure I'm not alone in doing this.

For work-related activities, etc, I tend to use LinkedIn.

Best regards,

Darren

-Original Message-
From: lindsay.yo...@rockets.utoledo.edu
Sent: Thu, 11 Jun 2015 14:40:31 +
To: rietveld_l@ill.fr
Subject: Re: Powder Diffraction Discussion Group on Facebook

As one of the younger members of the list, I would like to add a few
points.



I may never have found this list on my own if my advisor was not kind
enough to point it out to me. I have never seen a mailing list before
in my life :) To that end social media outlets may be helpful for
newcomers.  But I am very happy to be a member and will gladly
learn/join whatever format is chosen. So many people helped me get to
where I am today by kindly answering my basic questions that I feel
obligated to do the same for other newcomers.



I strongly believe in open-mindedness toward the new. Regardless, I
think that social media may be most useful for publicity and outreach
if we wish to seek out new members, but I don't think social media
formats are friendly to discussion. Facebook's format, for example,
would not allow for easy archiving of replies and they would easily
become buried as time passed. Another problem with social media is
that for those who are at work or school, being seen on facebook or
other social media may be forbidden if not frowned upon, even if they were 
being honestly productive.



I agree that fewer streams of consciousness are preferable. If we wish
to move at all, I propose that a forum format may be the best for
consideration?


__
__


From: rietveld_l-requ...@ill.fr rietveld_l-requ...@ill.fr on behalf
of Daxu Liu daxu...@yahoo.com
Sent: Thursday, June 11, 2015 9:06 AM
To: Leopoldo Suescun; rietveld_l@ill.fr
Subject: Re: Powder Diffraction Discussion Group on Facebook



Dear prof. Suescun,

I agree with you, and I have written to you some times ago. You do be
an enthusiastic and generous man. Thank you very much!

Yes, many beginners do ask lots of basic points on crystallography and
some basic steps on how to use some refinement programmes, and I was one of 
them.
However, someone has no choice to ask someone for help because he/she
maybe study oneself, and crystallography is not his/her major. I was
crazy on the Rietveld method in the past just for the interest, and I
had to write to some people for help because I can not solve some
problems even after I searched the answers in Google or other search
engines. I am very appreciated for those people who helped me like you
and Dr. Toby, Brian H., and Dr. Rodriguez-Carvajal, J. and other respectable 
and kind people.

I have studied the Rietveld method for eight years myself through the
web and reading some books, and I have published few papers on it,
which are colsely related to my research areas.

In a word, I feel, if you know about it and have spare time, it will
be possible to encourage and help someone greatly when you answer his
or her some basic questions (maybe stupied questions,:) ).

Best regards, Daxu




__
__


From: Leopoldo Suescun leopo...@fq.edu.uy
To: rietveld_l@ill.fr rietveld_l@ill.fr
Sent: Thursday, June 11, 2015 4:33 PM
Subject: Re: Powder Diffraction Discussion Group on Facebook



Dear Colleagues,
IMHO the Rietveld List is for rather advanced

Re: Politics-RE: Powder Diffraction Discussion Group on Facebook

[Lubomir Smrcok]

 and more younger and not quite
colleagues are using them too, for dissemination of careers, teaching
programs, events, job advertising, and even knowledge, so denying that
Facebook, Twitter, Research Gate, etc. may be of help to disseminate the
Rietveld Method in particular and knowledge in general is like denying
reality.

I?m not going to judge if the for-profit, business oriented attitude of the
companies that manage these social networks is favorable for spreading
science or not (probably not), but it may be a good idea that we use the
networks to allow younger colleagues becoming crystallographers to learn the
science from scientists and eventually lead them to the Rietveld List when
they have enough knowledge to ask meaningful questions.

Actually the IUCr (our IUCr) is in Facebook and I have participated in
discussion where it is is looking for ways to spread the knowledge by all
possible means, so I bet authorities will salute this move towards modern
(not necessarily better, I agree) tools.

As much as I have replied to crystallography questions in this list and
Research Gate I?ll do the same on Facebook, Twitter or whatever other forum I?m
at, and will suggest students seeking for deeper understanding to walk the
way by themselves reading books, papers and why not the Rietveld Mailing
Archive, and eventually seeking support from well trained scientists in the
Rietveld List. And I foresee many links in Facebook to the
rietveld_list_archives for everyone to use this accumulated knowledge,
while Mark Zuckerberg tries to sell them X-ray instruments, or X-files DVDs
or X-plane tickets or whatever the automatic software that drops
advertisement in our screen understands of what we talk about...

With best regards,

Leo

* List of important labs and universities I found in Facebook in 1 minute
search:

https://www.facebook.com/iucr.org?fref=ts

https://www.facebook.com/cnrs.fr?fref=ts

https://www.facebook.com/pages/Institut-Laue-Langevin-ILL/148452651846298?f
ref=ts

https://www.facebook.com/pages/DESY/103119693061304?fref=ts

https://www.facebook.com/MITnews?fref=ts

https://www.facebook.com/imperialcollegelondon?fref=ts

need more?

 --

Enviado desde mi m?vil.
Prof. Dr. Leopoldo Suescun
Cryssmat-Lab/DETEMA,  Facultad de Qu?mica,  Universidad de la Rep?blica,
Montevideo,  Uruguay.

El jun 9, 2015 4:15 AM, Radovan Cerny radovan.ce...@unige.ch escribi?:

Too many channels = crystallographer's death (freely translated from an old
proverb Too many hunters= rabbit's death).

Rather to express my opinion that if you have too many options where to look
for an info, you spend too much time before you find it.
Why the troglodytes should learn Facebook? Why do not the younger and more
up-to-date researcher use the email?


Radovan Cerny
Laboratoire de Cristallographie, DQMP
Universit? de Gen?ve
24, quai Ernest-Ansermet
CH-1211 Geneva 4, Switzerland
Phone  : [+[41] 22] 37 964 50, FAX : [+[41] 22] 37 961 08
mailto : radovan.ce...@unige.ch
URL: http://www.unige.ch/sciences/crystal/cerny/rcerny.htm


-Message d'origine-
De : rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] De la part
de LUIS MARIA RODRIGUEZ LORENZO
Envoy? : mardi 9 juin 2015 08:15
? : rietveld_l@ill.fr
Objet : Re: Powder Diffraction Discussion Group on Facebook



hehe, well played Lubo. People can define themselves as they wish, the
problem is the impression we produce in others with our self-definitions.
still the more channels people have to reach information , the best, and as
someone says before, if it does not work it will fade out with no damage.


Quoting Lubomir Smrcok uachs...@savba.sk:


Dear Luis,

I always find weird and sort of funny when someone cannot accept that
some people could call themselves troglodites meaning that they are
not very enthusiastic about ALL what other people call new and
progressive or even an innovation. This is how I understand Larry's
comment.

Personally, though I am younger than him I do not feel like a
second-rate human being or depleted of any important scientific
information when I completely ignore facebook and its clones. This way
of communication or, better, its information contents, strongly
resembles that described in Brave New World by A.Huxley. Though
published in 1932, it has been somehow ahead of the times.

A word of warning for facebookers : be careful, this is a book (check
the word with any good on-line service).  Fortunately, it is offered
also for Kindle so no worry for being seen with a pretty thick piece
of paper.

Best,
Lubo




On Tue, 9 Jun 2015, LUIS MARIA RODRIGUEZ LORENZO wrote:



Dear all,

Although not an active player on this list, except maybe in my early
days in late 90,s,(science , took me in a different
direction) I still keep track of what is happening in the Refinement
world and i would like to add my thoughts on this non technical
matter.
The generation of people called millennials  and young scientists
among them, get inform through facebook

Re: Powder Diffraction Discussion Group on Facebook

[Lubomir Smrcok]

!

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On 12 June 2015 at 01:40, Lubomir Smrcok uachs...@savba.sk wrote:
  But not through Rietved_l as Allan has forbidden attachments :-)
  lubo


  On Thu, 11 Jun 2015, Cline, James Dr. wrote:

I'll send you a copy of the selfie...


James P. Cline
Materials Measurement Science
Division  
National Institute of Standards and Technology
100 Bureau Dr. stop 8520 [ B113 / Bldg 217 ]
Gaithersburg, MD 20899-8523    USA
jcl...@nist.gov
(301) 975 5793
FAX (301) 975 5334

-Original Message-
From: Lubomir Smrcok [mailto:uachs...@savba.sk]
Sent: Thursday, June 11, 2015 1:30 PM
To: Cline, James Dr.
Cc: rietveld_l@ill.fr
Subject: RE: Powder Diffraction Discussion Group on
Facebook

Well,
Strictly speaking, you are wasting your time in
(formally) two different ways :-) And you shouldn't
forget to tweet about it and to take a selfie while
typing

Re: Unit cell accessible volume

[Lubomir Smrcok]

Hi,
Platon provides a reliable estimate of volumes of voids. However, it does 
not, in fact it can't, tell you more about their shapes. But what is known 
are approximate volumes taken in structures by typical molecules, mostly 
by solvents. Of course, some flexible molecules could happen to be a 
source of fun ... Having calculated a volume of your molecule you can 
estimate if it could principally fit.

Hope it helps,
Lubo


On Wed, 10 Jun 2015, Othman Al Bahri wrote:



Dear all,



I am trying to calculate the void volume in a unit cell. I can estimate the
overall void volume manually by subtracting  the occupied space volume from
the total unit cell volume using VESTA. I am, however, interested in finding
out whether inserting certain molecules in the voids (without distorting the
structure) is geometrically possible. Is there a way to do this given the
complexity of some structures/superstructures and the large number of ways a
molecule can intercalate into a structure ?



Kind Regards,

Othman Al Bahri

UNSW - Sydney



++
Please do NOT attach files to the whole list alan.he...@neutronoptics.com
Send commands to lists...@ill.fr eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++

Re: Powder Diffraction Discussion Group on Facebook

[Lubomir Smrcok]

Dear Luis,

I always find weird and sort of funny when someone cannot accept that some 
people could call themselves troglodites meaning that they are not very 
enthusiastic about ALL what other people call new and progressive or 
even an innovation. This is how I understand Larry's comment.


Personally, though I am younger than him I do not feel like a second-rate 
human being or depleted of any important scientific information when I 
completely ignore facebook and its clones. This way of communication or, 
better, its information contents, strongly resembles that described in 
Brave New World by A.Huxley. Though published in 1932, it has been somehow 
ahead of the times.


A word of warning for facebookers : be careful, this is a book (check the 
word with any good on-line service).  Fortunately, it is offered also for 
Kindle so no worry for being seen with a pretty thick piece of paper.


Best,
Lubo




On Tue, 9 Jun 2015, LUIS MARIA RODRIGUEZ LORENZO wrote:



Dear all,

Although not an active player on this list, except maybe in my early days in 
late 90,s,(science , took me in a different direction) I still keep track of 
what is happening in the Refinement  world and i would like to add my 
thoughts on this non technical matter.
The generation of people called millennials  and young scientists among them, 
get inform through facebook and similar. That link them to several sources of 
information without attaching them to one single source .


A facebook page related and linked to this discussion group could be the gate 
to new researchers (students) to this page and have a positive influence on 
the size of this community and their access to the very specific questions 
and knowledge that are usually discussed here. Their alternative can be the 
use of the potent available software to have results without guidance (e.g 
after , no sensible responses have been obtained through linkedyn or research 
gate, to name some, because nobody with the right expertise is there). It 
does not have to be a different or parallel discussion group, and it does not 
imply that you have to join  or use any new group. it is most likely to have 
a positive effect or maybe just null in the worst scenario.


In a more personal opinion , i always find weird and sort of funny, when 
people, whose work is to develop and spread knowledge, is proud to be a 
troglodite and do not dare to experience innovation. Facebook does not 
change  the way Science should be done but it may change the way of 
communicating .


Please dont take offence for my last comment , that is out of my purpose.
Best regards
Luis



Quoting Reinhard Kleeberg kleeb...@mineral.tu-freiberg.de:

To be honest, I can't imagine that crystallographic knowledge can be 
effectively transmitted via facebook. Probably one could safe time by 
reading some basic textbooks instead of liking and following. The same 
holds for other asocial (Lubo, I like this statement!) networks like 
researchgate, what also waste the time even of uninvolved people by 
spamming, just for generating profits by the companies.


The central points have already been fixed by Alan:

The advantage of the Rietveld mailing list is that contributions
aren't anonymous, it is not commercial and no use is made of users'
information, publicity is limited, and there is a structured archive
of discussion that is open to all, even those who don't have an account.

This is like science should be. Alan, thank you very much for all your 
altruistic efforts with the list!

Greetings

Reinhard



Am 08/06/2015 um 14:00 schrieb Davide Levy:

I want say something more about my decision to open the group in FB.
There is many people the use the Rietveld method as a magic black box:
insert the data, read the cif of the phase and obtain the results. Then 
they

say twenty-one and forty-one when they see a symmetry group!
Maybe a POP-group in FB can teach more about crystallography to a larger
group of scientist!
this is my opinion.
Davide

-Original Message-
From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On 
Behalf

Of Lubomir Smrcok
Sent: 08 June, 2015 2:49 PM
To: Alan Hewat
Cc: rietveld_l@ill.fr
Subject: Re: Powder Diffraction Discussion Group on Facebook

Dear Alan,

There are plenty of people who call usage of so-called social networks 
(they

are, in fact, very asocial) a progress. I would suggest to consider De
gustibus non est disputandum, but also Duo cum faciunt idem, non est idem.

Although I am not member of any of those asocial nets and do not plan to 
be,

I sometimes think of the end of such services like Gopher. Maybe we have
around a generation, who prefers to share instead of to search, think 
write. What a prefect opportunity for commercial companies :-)

Best,
Lubo


On Mon, 8 Jun 2015, Alan Hewat wrote:


I can understand that people have different ideas about the ideal
format for discussion, and for some of us email may seem a little old
fashioned. I suppose

Re: Powder Diffraction Discussion Group on Facebook

[Lubomir Smrcok]

Dear Alan,

There are plenty of people who call usage of so-called social networks 
(they are, in fact, very asocial) a progress. I would suggest to 
consider De gustibus non est disputandum, but also Duo cum faciunt idem, 
non est idem.


Although I am not member of any of those asocial nets and do not plan to 
be, I sometimes think of the end of such services like Gopher. Maybe we 
have around a generation, who prefers to share instead of to search, think 
 write. What a prefect opportunity for commercial companies :-)


Best,
Lubo


On Mon, 8 Jun 2015, Alan Hewat wrote:


I can understand that people have different ideas about the ideal format for
discussion, and for some of us email may seem a little old fashioned. I
suppose we could also use Twitter or any of the other social chattering
forums. But multiple groups on the same subject disperses the available
information, and it would be good to have some kind of consensus rather than
individual initiatives. 
The advantage of the Rietveld mailing list is that contributions aren't
anonymous, it is not commercial and no use is made of users' information,
publicity is limited, and there is a structured archive of discussion that
is open to all, even those who don't have an account. 

I myself simply inherited the list, but think it worth maintaining, and
would discourage members from posting to multiple groups on the same
subject.

Alan. (What, me worry ? :-)

On 8 June 2015 at 09:24, davide levy davide.lev...@gmail.com wrote:

  Good Morning
  I created the Powder Diffraction Discussion Group on Facebook,
  to speak about powder diffraction, Rietveld etc..  open for all
  use powder diffraction.
  https://www.facebook.com/groups/1087352967946225/
  Davide


++
Please do NOT attach files to the whole list
alan.he...@neutronoptics.com
Send commands to lists...@ill.fr eg: HELP as the subject with no
body text
The Rietveld_L list archive is on
http://www.mail-archive.com/rietveld_l@ill.fr/
++





--
__
   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE 
alan.he...@neutronoptics.com +33.476.98.41.68
        http://www.NeutronOptics.com/hewat
__

++
Please do NOT attach files to the whole list alan.he...@neutronoptics.com
Send commands to lists...@ill.fr eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++

RE: Apologies... The No Attachment rule.

[Lubomir Smrcok]

Hi Rievelders,
Although I have gone in the past years a long away from 
daily rietvelding, from 
time to time I can't resist my temptation to comment on some posts (OK, 
if the cap fits ... :-) and some of the comments could be well called 
snarky.


But if  you read that someone i) in facts asks people to solve 
his problem ASAP, or ii)  a beginner without knowledge of elementary 
crystallography tries to refine ADP of a cubic special position, because a 
SW permits and complains about matrix problems, or iii) someone attempts 
quantitative standardless phase analysis of  mixtures of disordered minerals
whose structures are at maximum just  estimated ... etc., etc.. All right, 
you may accuse me of going too far, or of exaggerating but isn't it at least

half true ?

If it is a PhD student I always ask where's his/her supervisor ?

We could also ask the companies who claim that perfect (and I simply must 
add  here :  though physically 
or statistically impossible - not to speak of common sense  ... ) results 
can 
be easily achieved when their SW is applied. Should we tell them or better 
not as are we afraid ( I am not, I  do not apply :-) of loosing their 
sponsorships ?


Best,
Lubo



On Sun, 10 May 2015, Kurt Leinenweber wrote:



Hi,



The subject of snarky comments is a fascinating one.  I have definitely been
the recipient of snarky comments for some of my more stupid posts on this
list.  The good thing about them is that it lets you know that you are
saying or doing something, crystallographically speaking, that is really
unpalatable to someone out there, and you might need to know this for your
own good.  I have definitely been chastised and have learned some things
over the years by being forced to read a snarky response to one of my
posts.  But on the other hand, to a beginner a snarky comment can be
damaging.  However, these comments are not confined to mailing lists ? they
happen at conferences too and they are just part of the fabric of science. 
As long as the whole list does not descend into a chaos of snarky comments,

I think it?s OK to let them get through.  One possible remedy is for others
to come to the defence of a victim of excessive snarkiness.  I have seen
that happen on this list sometimes, and other times have been tempted myself
to intervene, though I usually have not been brave enough (especially when
the snark source is someone famous).



-  Kurt



From: rietveld_l-requ...@ill.fr [mailto:rietveld_l-requ...@ill.fr] On Behalf
Of Darren Broom
Sent: Sunday, May 10, 2015 3:36 AM
To: Alan Hewat; Leopoldo Suescun
Cc: rietveld_l@ill.fr
Subject: RE: Apologies... The No Attachment rule.



Hi Alan

Thanks for the explanation. The point about the archive seems to me to be
the most persuasive - I see what you mean. Providing the file sharing links
stay active that does ensure the archive remains useful without having to
host additional files on the archive server.

It does seem that removing any attachments automatically would be the best
solution. Hopefully Song Zhen's suggestion will help sort that out.

Incidentally, Jon nicely illustrated one of the things about the list that I
really appreciate, by posting an interesting link that I hadn't seen before
and probably wouldn't have come across otherwise.

Also, I wondered if you could set up SYMPA so that it strips emails of any
unnecessary snarkiness (above a predefined threshold)?

Best regards,

Darren



  -Original Message-
  From: alan.he...@neutronoptics.com
  Sent: Sat, 9 May 2015 11:39:46 +0200
  To: leopo...@fq.edu.uy
  Subject: Apologies... The No Attachment rule.

Dear Rietveld list.



Good to see so many people asking for the list to be continued. And
even an example of an interesting scientific question immediately
answered by an expert. Encouraging.



So why do I forbid sinful attachments ? (No, it's not because I'm
getting old and snarky, though we all do eventually :-) Think of the
Rietveld list as a kind of relaxed Twitter, except that you are not
limited to 140 characters. And what about Google's decision this month
to favour sites that can be used on a mobile phone ? Yes, even oldies
use mobile phones for email. SMS is another example of beauty in
brevity. 




Then the Rietveld Archive is an excellent record of past discussions -
without the attachments. Messages that rely on attachments are then
often incomprehensible - look up that message on
https://www.mail-archive.com/rietveld_l@ill.fr/ Frankly, if you need
more than that, put it on a webserver with a link to it. Such links
are preserved in the archive.



If you see my own warning about no attachments as an attachment :-)
perhaps you should check how your email client is set up. Or tell me
how I can do it differently with SYMPA www.sympa.org I didn't design
the mail server nor the mail archive. Clearly, it is difficult to
enforce a simple no attachments rule, so what would it be like
policing a small attachments 

looking for a copy - thanks

[Lubomir Smrcok]

Thanks to all who sent me copies, I really appreciate your help !
Yours,
Lubo



-- Forwarded message --
Date: Tue, 24 Mar 2015 12:39:17 +0100 (CET)
From: Lubomir Smrcok uachs...@savba.sk
To: rietveld_l@ill.fr
Subject: looking for a copy

Hi,
May I ask someone of our Russian colleagues to provide me with an electronic 
copy of the paper by Arakcheeva et al., which has appeared in Kristallografiya 
2004 49 75 91  ?
The title of the paper (in English) is Structure type of hexagonal tantalum 
bronzes with variablecomposition K6 Ta6+z O15 F6 (F,O)y: Ta-bronzes and 
Ta-compounds


My apologies, but our collection of Kristallografiya ends in 1990.

Best,
Lubo


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looking for a copy

[Lubomir Smrcok]

Hi,
May I ask someone of our Russian colleagues to provide me with an 
electronic 
copy of the paper by Arakcheeva et al., which has appeared in 
Kristallografiya 2004 49 75 91  ?
The title of the paper (in English) is Structure type of hexagonal 
tantalum bronzes with variablecomposition K6 Ta6+z O15 F6 (F,O)y: Ta-bronzes and Ta-compounds


My apologies, but our collection of Kristallografiya ends in 1990.

Best,
Lubo


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++

winplotr 2006 Mac

[Lubomir Smrcok]

Hi,
Sorry for writing in the night, but does anybody know someone, who could 
provide a qualified support for Wiplotr-2006 ? My Mac version is of June 
2012. I would be really happy to have a manual just for that version, as 
the common version of Winplotr ( Windoze one) does not work on Mac 
within FullProf Suite ...


Best,
Lubo

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++

Re: FullProf

[Lubomir Smrcok]

well,
do you know why are you refining just that parameter ?
lubo


On Wed, 14 Jan 2015, Josh Kim wrote:


Dear Rietvelds,

I am new to FullProf, and am familiar with the difficulty in preparing a decent 
.pcr file, but have run into a problem to which I cannot pinpoint the error: 
During the first iteration of refinement I get the following message:

Singular Matrix!! Problem with SyCos_pat1 no.: 1?

Any ideas? I can provide the .dat and .pcr file if anyone is interested

Thanks
Josh
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++

Re: Statistics on semi-quantitative XRD data

[Lubomir Smrcok]

This is the best description of quantitative phase analysis by X-rays I 
have ever read ...


Very true is especially this part :
... is attributed to data where an estimationof errors is missing,  that 
have been never cross-checked by an

independent method, and so they are suspected to be biased by serious
systematic errors. If so, than datasets originating from different
sources cannot be treated seriously together in a statistical
evaluation, per definition.

Thanks a lot !

lubo


On Fri, 14 Nov 2014, Reinhard Kleeberg wrote:

I don't think that the term semi-quantitative is defined sharp enough to 
provide a basis for a serious statistical evaluation. In geosciences 
typically semi-quantitative is attributed to data where an estimation of 
errors is missing,  that have been never cross-checked by an independent 
method, and so they are suspected to be biased by serious systematic errors. 
If so, than datasets originating from different sources cannot be treated 
seriously together in a statistical evaluation, per definition. In the best 
case, they can be used to compare samples of one series measured with the 
same instrument and analyzed by the same procedure. Unfortunately many 
authors report wt% even in semi-quantitative phase analysis, what 
suggests compatibility. This is misleading and should be avoided. For the 
statistical evaluation of a series of comparably measured diffraction 
patterns of one geological object it seems more serious to apply cluster 
analysis of the raw patterns or to use any intensity ratios. But of course 
the best way is to improve the evaluation method to be really quantitative, 
i.e. free of systematic error and evaluated by realistic e.s.d.'s.


Reinhard Kleeberg

Am 13/11/2014 18:53, schrieb James Talbot:

Hello All,

I had the following request from a client:

I am looking for examples of statistics used on semi-quantitative data, 
i.e. comparing XRD results of multiple samples.  Do you have any 
recommendations or know of any papers that clearly explain their 
statistical methods?  In so many papers, it is glossed over.  I have a 
pretty good handle on my stats, but would prefer to see what other have 
done with XRD datasets.


Can anyone help with this.?  I do not know of any of the top of my head.

Thanks in advance,
James Talbot


K-T GeoServices, Inc.
970-641-1235 (office)
940-597-9076 (mobile)
219 North Iowa Street, Unit J
Gunnison  CO  81230-2479
www.ktgeo.com



--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg

Tel.++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129


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++

Re: on high pressure data indexing and unit cell reduction

[Lubomir Smrcok]

Hi,
I really enjoy your arguing ... The cell got by Topas is correct and the 
other programs fail to support this idea. Try ITO ... if you have at least 
20 peaks.


Back to real life where  gems do not rule. To check a  cell I can 
only recommend a standalone program nicknamed LePage, which is really 
good. A good trick I frequently use is to take any working input to 
Platon in any format, edit the cell and run it with Calc all. Of course, 
you will get a lot of rubbish, but at the very beginning there's also a 
good cell analysis.


A hint : if you have troubles with a cell, why not to post it :-) ?

Happy indexing,
lubo





On Mon, 3 Mar 2014, Young, Lindsay wrote:



Hello all - I've gotten stuck at a point in my data refinement, I'd
appreciate it if someone has any suggestions for me.


I have been trying to index high pressure data. It was collected using a
diamond anvil cell with a 2d detector. I integrated the data on GSAS II,
using the penetration correction. I opened this data on Jade to do peak
fitting, and indexed the resulting peak list in Topas. I managed to get a
reasonable monoclinic cell - but it is not in standard cell notation - the
angle for beta is 142 degrees, and I would like see this cell represented
such that is between 90 and 130 degrees. 



I tried indexing this peak list in Treor and Dicvol, with no
results. I then tried putting the unit cell from Topas into hklgen, taking
the peaks it generated (which do match those in the pattern), and indexing
them with Treor and Dicvol, but neither program turns out any results. I did
tweak the standard settings of both programs to try to get results, but this
was not successful. 



The idea is, if we can get the same result in another program as we did in
Topas, it could further show that the result is correct. 



Does anyone know how I can convert this cell? Is there a unit cell reduction
program I could use? If you need any additional information please let me
know!



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++

Re: Unrestrained SDPD future

[Lubomir Smrcok]

Hello everybody,

the fact than many papers presenting results where refinements are flooded 
by tsunami of restraints appear, is main responsibility of referees and 
editors. For instance, CIF dictionary clearly defines restraints items, 
but they do not appear in many published CIF's. Good question is if 
standard refinement program generate these item in their CIF outputs.


I would also end with a quote, if you don't mind. Here it is :
Common sense is not so common (attributed to Voltaire, but I guess this 
problem was common even in ancient Egypt even if not before ...)

lubo


On Fri, 9 Aug 2013, Alan Hewat wrote:


http://dx.doi.org/10.1107/S1600536813017522
proposed as an instance of the SDPD future trend


Fortunately this short paper is open access.
http://journals.iucr.org/e/issues/2013/07/00/vn2075/vn2075.pdf

It is truly a tour de force to quote N-H bonds determined to 3
significant figures from a heavy atom compound with one axis as long
as 17.5 Angstroms - by x-ray powder diffraction !

The future isn't what it used to be (Paul Valery, French poet)

Alan
__
Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
alan.he...@neutronoptics.com +33.476.98.41.68
   http://www.NeutronOptics.com/hewat
__

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++

Re: chi^2 smaller one

[Lubomir Smrcok]

Ignore it and mind the refined structural data ...
Lubo




On Tue, 23 Mar 2010, Christina Drathen wrote:



Dear all,

I am working on a refinement of synchrotron-X-ray powder data; the fit
is ok (though certainly not perfect) but I ended up with a confusingly
small reduced chi^2:
Rp = 23.4%
wRp = 16.9%
F^2 = 18.6%
chi^2 = 0.755
(1733 observations, 15 variables).

I would be very grateful for any suggestions on how to solve this problem.

Regards,
Christina

--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

Re: diffraction patterns or spectra

[Lubomir Smrcok]

Spectrum:
from Latin spectrum appearance, specter, from specere to look, look at


Lubo


On Thu, 11 Feb 2010, amar...@chimica.unige.it wrote:


Dear all,

I see that in scientific literature (also in  high-impact factor scientific
journals) the diffraction patterns are often referred to as diffraction
spectra. But we all know that diffraction is not a spectroscopic technique.
Should we pay more attention on this aspect when we write or refer a paper?
What about?

Best regards,
Alberto

Re: Negative Biso / absorption in TOPAS.

[Lubomir Smrcok]

Jacco,
could you kindly tell us the composition of the sample and the technique 
used to collect the data ?

Lubo


On Wed, 10 Feb 2010, Jacco van de Streek wrote:


Dear colleagues,

I am helping some people from the University of Frankfurt with their
Rietveld refinements, and usually their powder patterns are measured on
their own instrument and the refinements are excellent. This time,
however, they have to work with a powder pattern that was sent to them.
It is laboratory X-ray data, copper radiation, visible peaks out to 60
degrees 2theta, reasonable counting statistics, almost certainly flat
plate (reflection). The crystal structure is known. For the refinement,
they have TOPAS available.

The Rietveld refinement progresses very smoothly, but when the global
Biso is refined, it becomes very large and negative (-4). If we allow
the Biso to become negative, the difference curve is a flat line, in
other words, the fit is perfect. If we fix the global Biso at, say, 3.0,
the fit is still very good, but not as good as we are used to and the
difference curve starts to show some small residuals. We have no
experience with this, but some Google searches suggest absorption as
the problem. We have already modelled anisotropic peak broadening and in
our experience the background is modelled very well in TOPAS and does
not correlate with other parameters.

So our main two questions are:

1. Is absorption indeed the most likely cause of this problem or are
there other possibilities?

2. How do we model absorption in TOPAS? Which keyword do we use and what
are reasonable values for the parameters in the expression?

Best wishes,
--
Dr Jacco van de Streek
Senior Scientist
Avant-garde Materials Simulation
Freiburg im Breisgau, Germany

journal

[Lubomir Smrcok]

Pardon me,
this is definitely not a question touching rietveld, but I am a little 
bit lost. I do need full reference to the paper published in
CRyst. Struct. Commun. (1973) I did my best to google out a link to it, 
but with 
no success. Could anybody give me link to this journal ?

Many thanks,
Lubo

Re: scattering factor for B+3

[Lubomir Smrcok]

Just one question : have you asked your supervisor before sending such a 
mail ? Though I understand your position it seems that  you are not very 
familiar with the background of the method ...

lubo


On Thu, 26 Feb 2009, veron wrote:


Hello. I am a PhD student and need your help.

I am currently investigating the structure of an aluminosilicate with boron
substituted for aluminium by X-ray diffraction. Using Rietveld refinement, I
am trying to determine the respective positions of the boron and aluminium
sites within the structure, as well as their occupancies, and to follow the
structural evolutions when the boron content increases. Unfortunately, there
seems not to be any tabulated scattering factor for B+3, neither in the
refinement softwares (I use Fullprof) nor in the International tables for
X-ray crystallography?

Could someone tell me what the correct procedure for my study would be? I
first tried to define all the atoms as neutral and I am quite happy with the
fit obtained. But this does not really sound true. Should I better use Al3+,
Si4+, O2- and Be2+ (same electron number than B3+ but probably not the same
sin/theta*lambda evolution) ?

Thanks for your help.


Emmanuel Véron

CEMHTI-CNRS
Orléans-FRANCE

**

Emmanuel Veron

CNRS - CEMHTI

Tel. 02.38.25.55.32

Mail ve...@cnrs-orleans.fr

**

Re: Program for checking symmetry

[Lubomir Smrcok]

Try Platon by Ton Spek.
Lubo


On Wed, 5 Nov 2008 [EMAIL PROTECTED] wrote:


Dear all,

Recently, I have refined the structure using powder data. In each asymmetric 
unit of Pmc21, there are two chemically similar but crystallographically 
different complexes. The center of these two complexes is rougly around 
0,0,0.75. Therefore, the true space group may not be Pmc21. I am glad to know 
if there is a software to detect symmetry and suggest probable space group.


Thank you very much.

best regards
stephen

Re: Goodness of fit criterion

[Lubomir Smrcok]

Hi,
S is, strictly speaking a valid criterion only under special conditions 
which are not fulfilled in Rietveld. My advice is to forget about the 
value of S and think of physics, i.e. bond distances, angles, occupancies 
and in favorite cases, also of displacement parameters.

Lubo


On Tue, 3 Jun 2008, Franz Werner wrote:


Dear Rietvelders

I've a basic question on the Rietveld agreement index S (goodness of fit) . In The Rietveld 
Method (ed. R.A. Young) it says in chapter 1.4 An S value of 1.3 or less is usually 
considered to be quite satisfactory. An S value of 1.7, for example, probably is a warning that you 
should look further into the reasons and question the adequacy of your model. In the 
literature, however, papers are published quite frequently with considerably larger S values (I'm 
just looking at an Acta Cryst. B paper with S values between 6 and 8.5).

The question is now how strict has the 1.3 limit to be applied, what is the largest 
acceptable S value? How does one assess S1.7 and justify it to referees?

I should add that I'm not a follower of the R-value cult but think that the 
most important criterion is chemical and physical plausibility.

Thanks for your advice.

Franz Werner
--
Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen!
Ideal für Modem und ISDN: http://www.gmx.net/de/go/smartsurfer

Re: RES: ADS

[Lubomir Smrcok]

Hi,
I really wonder why do you bother about 1% difference when the error of 
the method (XRD, quantitative phase analysis) could reach 10% 
(absolute) ...

People in the discussions appearing here seem to forget about two things:

i) quantitative phase analysis done by rietveld method is always 
re-scaled to 100%, i.e. the accuracy of % attributed to the individual 
phase directly depend on %'s attributed to the another phases present in 
the mixture (i.e. when you forget or ignore one phase having 10% share, 
those %'s are redistributed among the other phases);


ii) this method completely ignores any amorphous parts (i.e. those not 
providing Bragg peaks, to be more exact) - ignores, because it cannot do 
anything else about it. Obviously, when you compare XRF and XRD you can 
find yourself in troubles as XRF dos not bother about the state of the 
compounds.


Finally, my personal advice. If someone tells you you can analyze clinkers 
or even cements by XRD accurately, do not trust him. He, most probably, 
thinks of selling you a machine you can hardly use for this purpose :-)

Bad luck if you have already bought it ...

Best,
Lubo



On Thu, 29 May 2008, [iso-8859-1] José Carlos Cordeiro wrote:


My samples are cements (fine samples with 30 microns) and don't need micronize 
its. The problem in my refinements is that periclase quantified with fixed slit 
is bigger than MgO by Fluorescence, and its impossible. Ex:



Periclase with fixed slit: 7,14%

MgO by XRF = 6,84%



We know that part of MgO (1,5-2,0%) go to the structure of C3S an C2S phases, 
so periclase expected in this sample is 4,8% - 5,3%. If we consider this, the 
errors of refinement is not  very slim.



Sorry for my bad English!!!



regards



===

José Carlos Cordeiro

Diretoria Técnica - Laboratório Central

Centro Técnico - Curitiba

Rodovia PR-092, 1303, Abranches, 82130-570 Curitiba-PR

Votorantim Cimentos

[EMAIL PROTECTED] mailto:[EMAIL PROTECTED]

www.votorantimcimentos.com.br

Fone: + 55 041 3355-1380

Fax:   + 55 041 3355-1358

===

-Mensagem original-
De: Whitfield, Pamela [mailto:[EMAIL PROTECTED]
Enviada em: quinta-feira, 29 de maio de 2008 17:40
Para: José Carlos Cordeiro; rietveld_l@ill.fr
Cc: Mitchell, Lyndon
Assunto: RE: ADS



Hi Jose



Errors in the region of 1wt% aren't unheard of in complex mixtures (and the 
liklihood of the second decimal place being meaningful is very slim).  However 
there are other possible explanations and one in particular comes to mind.

Did you micronize your sample?  If yes then feel free to ignore the following!  
If not then it might be worth thinking about.



We did a systematic study on the effect of particle statistics on the 
repeatability of quantitative analysis on one of the NIST cements last year 
(presented at the ICCC in Montreal - should really go somewhere more 
accessible).  We compared different divergence slits, micronized and 
unmicronized samples, spun and static, and remounted/repeated the experiments 3 
times each for real statistics as opposed to esds.



Funnily enough the phase that showed the biggest anomaly in one of the unground 
sample was the periclase - obviously a big (by XRD standards) lump fell into 
the sample from the kiln that made up the NIST batch and made it through the 
mill at the plant.  Without grinding it we got 0.1, 0.1 and 2wt% one series of 
3, versus 0.6, 0.6 and 0.6 wt% (this is from memory so don't don't quote me!) 
for the micronized sample.

This was the result that we should have got theoretically but it was nice to 
see it work in practice, and the periclase did such a nice job for us by 
sticking out like a sore thumb even without a Rietveld analysis!  BTW there was 
no statistically significant difference (95% limits) in the results of the C3S 
and C2S phases between ground and unground samples - mostly because the errors 
in the unground samples were so large!  The minor phases were another matter.  
In the micronized samples the choice of divergence slit size made little 
difference, but with the unground samples they made a significant difference.



To cut a long story short it all comes down to particle statistics - with an 
ideal powder the choice of fixed versus variable slits (or even different fixed 
slits) should make no difference (assuming that the Rietveld software can 
handle the difference in profiles).  Moral of the story - sample prep, sample 
prep and more sample prep!



Pam

-Original Message-
From: José Carlos Cordeiro [mailto:[EMAIL PROTECTED]
Sent: May 29, 2008 3:53 PM
To: rietveld_l@ill.fr
Subject: ADS

I have a Programmable Divergence Slit (incident beam) in my 
difratctometer, that can work in automatic mode (irradiated length) or fixed 
mode (0.5 degree or 1.0 degree etc). What is the best collect mode for Rietveld 
Refinament??



I did refinement two 

Re: Neutron or X-ray?

[Lubomir Smrcok]

On Sun, 9 Mar 2008, Alan Hewat wrote:


Precision of CW neutron machines is
frequently not so high as X-ray diffractometers, but this problem is
masked in Rietveld by extremely (artficialy) low e.s.d.'s of lattice
parameters.


Hmm?? With CW neutron machines, the wavelength is sometimes not well
defined so there may be a scale error in the refined lattice parameters.
Lattice dimensions are then precise but not accurate

OK, THIS IS MY MISTAKE, YOU ARE RIGHT.


 until they have been

corrected for this scale error. But that has nothing to do with the
accuracy with which the atom coordinates are determined.

IT HAS NOT IF YOU THINK OF FRACTIONAL COORDINATES. IN THE LAST STEP YOU 
SHOULD, HOWEVER, TRANSFORM THEM TO CARTESIAN AND THE ACCURACY OF 
THE TRANSFORMED VALUE WILL BE TOUCHED BY THE ACCURACY OF THE LATTICE 
PARAMETERS.


YOURS,
LUBO SMRCOK

Re: Neutron or X-ray?

[Lubomir Smrcok]

Hello,
do not mind statistical precision (your error at the oxygen coordinate) 
and look at the errors (e.s.d.) of the interatomic distances, especially 
of those between bonded atoms. Precision of CW neutron machines is 
frequently not so high as X-ray diffractometers, but this problem is 
masked in Rietveld by extremely (artficialy) low e.s.d.'s of lattice 
parameters. On the other hand, what you are looking for is not PRECISION, 
but ACCURACY. Heating a sample on a standard BB X-ray machine is a good 
source of systematic errors in the data which transform to the lattice 
parameters. This is not the case in neutron experiment.

My advice is to look also at O-O distances.
Best wishes,
Lubo



On Sun, 9 Mar 2008, Davide Levy wrote:


Dear All,

I have a ”philosophic” question for you: the structure obtained by NPD are
better than the ones found by XRPD?

I explain a little bit more my question, I studied a MgAlFeO4 spinel both by
NDP and XRPD from RT to 1000°C. The O coordinate it is different for two
data set (0.2581 vs.0.25953). The found error on the oxygen coordinate is
about 10-5 and 10-4  for NPD and XRPD data respectively. The coordinate
calculated from cation partitioning and cation radii is similar to the XRPD
result.

At the moment I did not found a justification of this and I do not know
which result  is the ‘right one’.

Do you have any suggestion?

Thank you

Davide

RE: advice on new powder diffractometer

[Lubomir Smrcok]

Gentlemen,
I really do not want to interfere too much, but you should (probably) 
start with the definition of noise and signal. In the theory of 
signals both terms have their well-defined meaning. So you can either 
accept the definition used by the signal community and identify what is 
what in your powder patterns or develop your own definition and put it on 
a good statistical base.

My apologies once more,
Lubo


On Tue, 19 Feb 2008, Michael Glazer wrote:


Alan
I absolutely agree with you regarding Rietveld refinement. The same
argument is true for adjusting peak shapes to get the best fit, playing
around with different peak formulae. Often such tweaking, while it makes
the observed and calculated fit look nicer, has little effect on the
atomic positions, which in the end is what one is trying to derive. One
should not lose sight of the model.

But my question about defining SNR is more to do with the use of powder
data in general, and especially as used in industry or forensics. For
example distinguishing in a legal sense between two materials may depend
on which of two powder patterns has the higher SNR. I keep seeing this
term used in papers and books but never defined.
Mike

-Original Message-
From: Alan Hewat [mailto:[EMAIL PROTECTED]
Sent: 19 February 2008 10:10
To: rietveld_l@ill.fr
Subject: RE: advice on new powder diffractometer


So my question remains: what is the definition of signal to noise
ratio that is accepted for powder diffraction?


Why does it matter? A higher Bragg/Background ratio does not necessarily
mean better data if counting statistics are poor. Exaggerating slightly
:-) consider a single peak with a ratio of 100/1 compared to a peak with
a ratio 1/1000. The second measurement will give the lowest error,
not the first which has a much higher signal/noise. And you measure lots
of points on a slowly varying background, so you have a much better
estimate of background than the normal error of a single point. Please
don't encourage people to simply maximise signal/noise.

Similarly, low profile R-factor's can be obtained with low resolution
data and high background. That does not mean that low resolution data
produces smaller errors in structural parameters.

I worry about people treating measurement and refinement as black boxes
with simplified measures of quality such as R-factors, signal-to-noise
etc. You have to look at the physical reality of the model and the
estimated errors in its parameters, while not cheating by removing data
that doesn't fit for unknown reasons, adding too much a priori
information such as constraints, or throwing in extra garbage parameters
to improve the R-factors.
__
Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE
[EMAIL PROTECTED] +33.476.98.41.68
   http://www.NeutronOptics.com/
__

RE: advice on new powder diffractometer

[Lubomir Smrcok]

IMHO,
plenty of counter problems have their roots in the past.  When 
the first GM counters were used in powder diffractometry the apparatus 
(both 
electronics  math) was taken directly from the field of \alpha-particles 
physics. 
Because \alpha-particles are rather rare (events), people used binomial or 
POissonian distributions with mean value=variance. This is hardly true for 
normal (Gaussian) distribution  diffraction. Later when the LS moved to 
the field of diffraction, 
weights were automatically set to w=1/var as if the random errors (=noise, 
or better, white noise) had normal distribution. So far so good, 
but  variance was set to 
the mean value as if it were Poissonian distribution. Because the LS are 
derived under the 
assumption of normal distribution of random errors, the procedure must 
give biased estimates of the parameters. Now when the solid state 
detectors are rather fast and efficient it is probably the high time for 
new data collection strategies, e.g. repeated measurements giving better 
estimates of the variances. In this way it could be possible to estimate 
also the noise level. Who knows, BTW :-0

Lubo


On Mon, 18 Feb 2008, Michael Glazer wrote:


How do you define signal to noise in powder diffraction? I have seen this term 
used several times, but I have not found a definition so far with regard to 
powder diffraction per se.
I have just done two runs on a Panalytical one with 0.04 soller slits and one 
with 0.02 (both with a CuKa1 premonochromator) both for about 9 hours. The 
strongest peak for the 0.02 case is 2700 counts, half width 0.08 degrees and a 
background of 25 counts. The same peak with the 0.04 slits  has 7 counts, 
half width 0.11 degrees and a background of 700 counts.


Mike Glazer

-Original Message-
From: Van der Lee [mailto:[EMAIL PROTECTED]
Sent: 18 February 2008 16:36
To: rietveld_l@ill.fr
Subject: Re: advice on new powder diffractometer

Leonid Solovyov wrote the following on 18/02/2008 16:27:

Yes it is mainly down to the Soller slits, there was a very large
thread on soller slits somewhere in the Rietveld archives about this
discussion. I think the down side of changing the soller slits is a
move away from the optimum FWHM that can be obtained?


Changing sollers from 0.04 rad to 0.02 or 0.01 reduces the asymmetry,
the FWHM and the intensity, so the peak shape and the resolution
become more optimal but the intensity is sacrificed.




However, the signal to noise ratio becomes better with 0.02/0.01 rad sollers 
compared to 0.04 rad

Arie


--
***
A. van der Lee
Institut Européen des Membranes
CNRS - UMR 5635
Université de Montpellier II - Case Courrier 047 Place E. Bataillon
34095 MONTPELLIER Cedex 5 - FRANCE

Tel :  33 (0) 4 67 14 91 35
Fax : 33 (0) 4 67 14 91 19

Website X-ray scattering facility ICG/IEM:
http://www.iemm.univ-montp2.fr/xrayweb/main_uk.html

glass crystalline

[Lubomir Smrcok]

Hello,
I was asked by my colleague if there is a way how to find (I'd prefer 
estimate) 
the amount of the crystalline phase in the glass matrix. Both phases have the 
same (or very close) chemical composition.
If necessary, they can also prepare the sample totaly crystalline without any 
glass.
My apologies for sending this problem to rietveld list, but I hardly know any 
better address :-)
To be frank : I do not expect to solve the problem using Rietveld as the 
structure of the crystalline phase is not very well known. They would prefer a 
relatively simple method for daily use in their lab.

Thanks on behalf of them.
Lubo

Re: transition aluminas (fwd)

[Lubomir Smrcok]

Hello,
try Acta Cryst C62 i83-84 (2006) and the references cited therein.
Best,
Lubo


On Thu, 6 Sep 2007, Laurent Favaro wrote:

 Dear Rietvelders,

 I am searching for the structure of various transition aluminas
 (especially rho, eta, khi, gamma, delta and sigma)
 to perform ab-initio calculations of their infrared spectra.
 Could you, please, inform me about those structures ?
 Best regards,

 Dr L. Favaro
 Laboratoire LEMHE
 Université Paris-Sud
 Orsay, France

Re: Problems using TOPAS R (Rietveld refinement)

[Lubomir Smrcok]

Gentlemen,
I've been listening for a week or so and I am really wondering what do you
want to get ... Actually you are setting up a refinement, whose results
will be, at least, inaccurate. I am always surprised by attempts to refine
crystal structure of a disordered sheet silicate from powders, especially
when it is known it hardly works with single crystal data. Yes, there are
several models of disorder, but who has ever proved they are really good ?
I do not mean here a graphical comparison of powder patterns with a
calculated trace, but a comparison of structure factors or integrated
intensities. (Which ones are to be selected is well described in the works
of my colleague, S.Durovic and his co-workers.)
As far as powders are concerned, all sheet silicates suffer from
prefered orientation along 001. Until you have a pattern taken in a
capillary or in transmission mode, this effect will be dominating and you
can forget such noble problems like anisotropic broadening.

Last but not least : quantitative phase analysis by Rietveld is (when only
scale factors are on) nothing else but multiple linear regression. There
is a huge volume of literature on the topic, especially which variables
must, which should and which could be a part of your model.
I really wonder why the authors of program do not add one option called
QUAN, which could, upon convergence of highly sophisticated non-linear
L-S, fix all parameters but scale factors and run standard tests or factor
analysis. One more diagonalization is not very time consuming, is it ? To
avoid numerical problems, I'd use SVD.
This idea is free and if it helps people reporting 0.1% MgO (SiO2) in a
mixture  of 10 phases to think a little of the numbers they are getting, I
would only be happy :-)
Lubo

P.S. Hereby I declare I have never used Topas and I am thus not familiar
with all its advantages or disadvantages compared to other codes.


On Wed, 21 Mar 2007, Reinhard Kleeberg wrote:

 Dear Leandro Bravo,
 some comments below:

 Leandro Bravo schrieb:

 
  In the refinement of chlorite minerals with well defined disordering
  (layers shifting by exactly b/3 along the three pseudohexagonal Y
  axis), you separate the peaks into k = 3.n (relative sharp, less
  intensive peak) and k #61625; 3.n (broadened or disappeared
  reflections). How did you determined this value k = 3.n and n =
  0,1,2,3..., right?
 
 The occurence of stacking faults along the pseudohexagonal Y axes causes
 broadening of all reflections hkl with k unequal 3n (for example 110,
 020, 111..) whereas the reflections with k equal 3n remain unaffected
 (001, 131, 060, 331...). This is clear from geometric conditions, and
 can be seen in single crystal XRD (oscillation photographs, Weissenberg
 photographs) as well in selected area electron diffraction patterns. The
 fact is known for a long time, and published and discussed in standard
 textbooks, for example *Brindley, G.W., Brown, G.:  Crystal Structures
 of Clay Minerals and their X-ray Identification. Mineralogical Society,
 London, 1980.*

  First, the chlorite refinement.
 
  In the first refinement of chlorite you used no disordering models and
  used ´´cell parameters`` and ´´occupation of octahedra``. So you
  refined the lattice parameters and the occupancy of all atoms?

 Yes, the lattice parameters.
 Only the occupation/substitution of atoms with significant difference in
 scattering power can be refined in powder diffraction. In case of
 chlorites, the substitution Fe-Mg at the 4 octahedral positions can be
 refined.

 
  In the second refinement, you use na anisotropic line broadening ´´in
  the traditional way``. So you used a simple ellipsoidal model and/or
  spherical harmonics?
 
 Simple ellipsoidal model, assuming very thiny platy crystals. But it was
 clear that this model must fail, see above the known fact of disorder in
 layer stacking. And from microscopy it is clear that the crystals are
 much too large to produce significant line broadening from size effects.
 You can see this for a lot of clay minerals: If the ellipsoidal
 crystallite shape model would be ok, the 00l reflections would have the
 broadest lines, and the 110, 020 and so on should be the sharpest ones.
 But this is not true in practice, mostly the hkl are terribly broadenend
 and smeared, but the 00l are still sharp.

  The last refinement, describing a real structure. You used for the
  reflections k #61625; 3.n (broadened peaks) a ´´rod-like intensity
  distribution``, with the rod being projected by the cosine of the
  direction on the diffractogram. You used also the lenghts of the rods
  as a parameter, so as the dimension of the rods for 0k0 with k
  #61625; 3.n. I would like to know how did you ´´project`` these rods
  and use them in the refinement.
 
  For the k = 3.n reflections, you used an anisotropic broadening model
  (aniso crystallyte size) and and isotropic broadening model
  (microstrain broadening). But you said that crystallite size is an
 

Re: Problems using TOPAS R (Rietveld refinement)

[Lubomir Smrcok]

Or, to see how bad the results from Rietveld refinements of  kaolintes are
try review
paper in
Zeitschrift fuer Kristallographie 210(3) 177-183, 1997
lubo smrcok


On Wed, 14 Mar 2007, Alan Hewat wrote:

 Reinhard Kleeberg said:
  There are not so much trials published to find a
  working solution for practical Rietveld quantification of clays. One
  would be a self-citation of a paper, so I can't do this here in the list.

 A good one is :-)

 Pitfalls in Rietveld Phase Quantification of Complex Samples
 R. Kleeberg (2005) Microstructure Analysis in Materials Science
 http://www.ww.tu-freiberg.de/mk/bht/Abstracts/kleeberg.pdf
 _
 Dr Alan Hewat, ILL Grenoble, FRANCE [EMAIL PROTECTED]fax+33.476.20.76.48
 +33.476.20.72.13 (.26 Mme Guillermet) http://www.ill.fr/dif/people/hewat/
 _

Re: FullProf problem

[Lubomir Smrcok]

Well,
if the only error in such a refinement were V0 instead of V4+ ...
Forget it and go on with neutral species. BTW, I wonder if a single
crystal refinement could distinguish between V4+ and V0 except for a highly
ionic compound ...
Lubo


On Thu, 28 Sep 2006, Daniel Toebbens wrote:

 Stanislav Ferdov schrieb:

 Dear All,
 
 I am trying to refine the structure of a porous
 vanadoslicate, however FullProf does not recognize the
 scattering coefficient of V4+. Does somebody know how
 I could modify the pcr file in order to work with V4+?
 
 
 Well, there just is no scattering factor for V+4 in the internal list,
 and I'm not sure
 there is some at all. However, V+3 and V+5 ARE in the list. I would
 suggest just
 defining a mixed occupation of those.

 Daniel Toebbens

looking for a post-doc

[Lubomir Smrcok]

Sent on behalf of my ex-PhD student who has not access to groups :

==
My name is Ondrej Pritula and I have recently finished my
PhD studies at the Institute of
Inorganic Chemistry, Slovak Academy of Sciences, Bratislava.

I am looking for a postdoc position in the field of materials chemistry,
X-ray and/or neutron diffraction.

The topic of my PhD. Thesis was Rietveld quantitative X-ray
and neutron analysis of Portland clinkers. The results have been reported
in three papers and presented at two EPDIC's.

At present I am working on:

i)  X-ray/neutron  qualitative and quantitative analysis and
SEM/EDX analysis SiC/Si3N4 nano/micro-composites,

ii) quantitative neutron and X-ray diffraction analysis of the ceramic
materials related  to the group of the alpha- and beta-SiAlONs,

iii) high and/or room temperature neutron and X-ray analyses of the
fluorite materials (K2TaF7 and of the systems related to Na3AlF6).
==

He is ready to answer all other questions at [EMAIL PROTECTED]
Best wishes,


Dr.Lubo Smrcok
Crystallography Laboratory
Department of Theoretical Chemistry
Institute of Inorganic Chemistry
Slovak Academy of Sciences
SK-845 36 Bratislava
Slovak Republic
E-mail : [EMAIL PROTECTED]
Voice : + 421 2 5941 0435
Fax :   + 421 2 5941 0444

Re: a few words about pdCIF

[Lubomir Smrcok]

Brian,
there is no reason to call your work "a thankless task". We all (I mean
powder diffractionist) owe you a lot for your effort to make our life
easier. It would be nice if you make public the subroutines you have
mentioned in your mail. THough I agree with you that for many of us it is
easier to write an email, there are still some enthusiasts.
Best wishes,
Lubo
 

On Fri, 5 Nov 1999, Brian H. Toby wrote:

 There are some very good subroutine libraries for reading and writing
 CIF files, but not many powder diffraction programs have been adapted
 for pdCIF yet. No commercial conspiracy here; it's just that these days
 most people seem to write e-mail rather than computer code.
 
 Brian
 

RE: Combined neutron/x-ray refinements

[Lubomir Smrcok]

On Tue, 25 May 1999, Alan Hewat, ILL Grenoble wrote:

 
 Mainly because the ESD's are only correctly calculated if the model
 is CAPABLE of fitting the data.  This is not usually true when systematic 
 errors are important compared to statistical errors, since the model is
 usually not capable of describing these systematic errors fully - 
 background, texture etc... 
 
...and weights.

Lubo

Re: Combined neutron/x-ray refinements

[Lubomir Smrcok]

On Mon, 10 May 1999, Armel Le Bail wrote:

 published combined X-ray and neutron refinements. Am I so far
 from the truth if I estimate the number of published works combining
 X-ray and neutron in a single refinement to, say less than 20 cases ? I 
 would like to see, in the 10 next years, this number increase to, say, 1000,
 for being convinced that this is really a way that should be adopted.
 But I do not believe it. Such combined refinements will stay anecdotal
 (or elitist if you prefer), reserved to specific cases, or to those having
 easy access to both radiations.
 
Armel,
this discussion has gone too far from the starting point. The question
really isn't "neutrons Yes/No", but if all of us have equal access to all
sources. People from both NIST, Grenoble or RAL would, no doubt, answer
yes, why not ?  Well, if I were there I wouldn't hesitate for a moment, 
but if I am outside, there are plenty of time and financial but NO
scientific constraints. I think the most of us would be happy if they
could access neutron sources as easily as their in-lab machines.
Do not agree, please. The days before GLASGOW are so boring ...
Best,
Lubo
 

Subroutine needed

[Lubomir Smrcok]

Hello,
does anybody know where is a source code of the subroutine called SYMOP
(SYMMOP) by H.Burzlaff ? It was designed to interpret a space group symbol
and provide a set of  rotational matrices and/or trans. parts.
Best,
Lubo Smrcok

P.F.'99

Re: [sdpd] Re: RIET/SDPD a suggestion...

[Lubomir Smrcok]

That's great to assume everybody uses the same  software as you do,
Armel ...
I think also CIF was developed to avoid thousands of formats. Why not to
standardize e-mail exchange first and only THEN proceed with powder data
:_)
Lubo

On Fri, 5 Nov 1999, Armel Le Bail wrote:

 html
 font size=3L. Cranswick wrote:br
 br
 gt;As while native data would be a good quality check -br
 gt;something like this of would need standard filebr
 gt;formats to be managable and of maximum usefulness -br
 gt;and that means CIF, and powder programs THAT CANbr
 gt;ROUTINELY import/write CIF structures and data(?))br
 gt;...br
 gt;br
 gt;Comments?br
 br
 When I read the introduction to Powder CIF at :br
 nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;
 a href="http://www.iucr.org/iucr-top/cif/pd/index.html" eudora="autourl"font 
size=3http://www.iucr.org/iucr-top/cif/pd/index.html/abr
 font size=3gt;quot;..the powder CIF effort had the additional goals
 of documentingbr
 gt;and archiving experimental data. It is intended that powder CIF
 bebr
 gt;used for communication of completed studies, but also for databr
 gt;exchange between laboratories. This is frequently done at 
 sharedbr
 gt;diffraction facilities such as neutron and synchrotron sources.
 Thebr
 gt;powder dictionary was written anticipating needs from
 conventionalbr
 gt;X-ray diffractometers, as well as from synchrotron, CW neutron,br
 gt;TOF neutron, and energy dispersive X-ray instruments .quot;br
 br
 Well, that is exactly what we want. But is there somewhere anbr
 archive already ? Not exactly in the sense of a what we expectbr
 (a free database, searchable online).br
 br
 And about conversion software, the list is quite short at br
 nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;
 a href="http://www.iucr.org/iucr-top/cif/index.html" eudora="autourl"font 
size=3http://www.iucr.org/iucr-top/cif/index.html/afont size=3nbsp;
 :br
 br
 nbsp;nbsp;nbsp; cif2sx, a CIF to SHELXL93 converter. br
 nbsp;nbsp;nbsp; DIFRAC, a package for translating diffractometer
 output frombr
 
nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;
 many systems to CIF. br
 nbsp;nbsp;nbsp; pdb2cif Version 2.3.7, a filter for translating PDB
 format filesbr
 
nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;
 to mmCIF. br
 nbsp;nbsp;nbsp; cif2pdb Version 1.0.1, a filter for translating mmCIF
 to PDBbr
 
nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;
 format. br
 br
 We would expect to find something like :br
 nbsp;nbsp;nbsp; POWCIF, a package for translating powder
 diffractometer ouputbr
 
nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;
 from many systems to CIF as well as for translatingbr
 
nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;
 reversely CIF to many data formats (diffractometer br
 
nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;nbsp;
 output and Rietveld software entries).br
 br
 But POWCIF does not exist (or am I wrong ?), and this is thebr
 main restraint to the Powder CIF use.br
 br
 So that, what are doing the guys that want to use a powder CIFbr
 file ? They edit the file and pick up the data, manually.br
 br
 Finally, I would ask a question. Why the producers of Powder CIFbr
 which quot;had the additional goals of documenting and archivingbr
 experimental dataquot; finally did not produce and organize the
 freebr
 archive ? Is it because of ICDD, which quot;has significant input,br
 along with others, for the design of this dictionaryquot; (the
 Powderbr
 CIF dictionary), and had the project to build a commercialbr
 database ?br
 br
 Having sponsors has to be paid somewhere...br
 br
 Best,br
 br
 Armel Le Bailbr
 font size=3a href="http://sdpd.univ-lemans.fr/course/" 
eudora="autourl"http://sdpd.univ-lemans.fr/course//abr
 br
 font size=3 /fontbr
 divArmel Le Bail - Universite du Maine, Laboratoire des
 Fluorures,/div
 divCNRS ESA 6010, Av. O. Messiaen, 72085 Le Mans Cedex 9, 
 France/div
 diva href="http://www.cristal.org/" 
EUDORA=AUTOURLhttp://www.cristal.org//a/div
 /html
 
 
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