Re: Rietveld website cancelled ?

[Kurt Leinenweber]

Was that Clint Eastwood?  - Kurt


From: rietveld_l-requ...@ill.fr  on behalf of Le 
Bail Armel 
Sent: Wednesday, August 29, 2018 12:01:25 PM
To: Rietveld_L@ill.fr
Subject: Re: Rietveld website cancelled ?


OK, seems that the SDPD book preface looks unclear to some.



Western movies adepts well know that sentence :

"You see, in this world there's two kinds of people, my friend: those with 
loaded guns, and those who dig. You dig. .."



Similarly, there are two kinds of people, those believing that the sense of the 
words "structure determination" and

"structure refinement" are the same, and the others. You dig.



Best



Armel









> Message du 29/08/18 18:09
> De : "Larry Finger" 
> A : "Le Bail Armel" , Rietveld_L@ill.fr
> Copie à :
> Objet : Re: Rietveld website cancelled ?
>
> On 08/29/2018 04:15 AM, Le Bail Armel wrote:
> > Hi,
> >
> > After the IUCr Monograph on Crystallography 13 (2002)
> >
> > entitled "Stucture Determination from Powder Diffraction Data"
> >
> > you may find in the preface :
> >
> > "Although the Rietveld method of structure refinement from powder
> >
> > diffraction data is often loosely considered to be synonymous with structure
> >
> > determination, it is not. The Rietveld method only comes into play in the
> >
> > final stage of the structure solution process when an approximate structural
> >
> > model has been found."
> >
> > WIF David, K Shankland, LB McCusker, C Baerlocher
> >
> > A clear distinction having my complete agreement.
> >
> > Armel
>
> Armel,
>
> Although the above statement may be generally true, I can provide a counter
> example. In Max W. Schmidt, Larry W. Finger, Ross J. Angel, and Robert E.
> Dinnabier, "Synthesis, crystal structure, and phase relations of AlSiO2OH, a
> high pressure hydrous phase", American Mineralogist, V. 83, 881-888, 1998, we
> only had a powder - no single crystals. From data measured at ESRF, we used 
> GSAS
> to isolate the peaks of interest for the unknown phase, and used program TREOR
> to autoindex the unknown and identify the impurity phases. We then extracted
> intensities using the LeBail method, and determined the structure using direct
> methods with program SIRPOW. The structure was then refined with GSAS. We were
> even able to locate the H atom from Fourier maps!
>
> Even 20 years ago, it was possible to determine the structure from X-ray 
> powder
> patterns.
>
> Larry
>
>
>
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Re: Rietveld website cancelled ?

[Larry Finger]

On 08/29/2018 02:01 PM, Le Bail Armel wrote:

OK, seems that the SDPD book preface looks unclear to some.

Western movies adepts well know that sentence :

"You see, in this world there's /two kinds/ of /people/, my friend: /those/ with 
loaded /guns/, and /those/ who /dig/. /You dig/. .."


Similarly, there are two kinds of people, those believing that the sense of the 
words "structure determination" and


"structure refinement" are the same, and the others. You dig.


I am happy to have been one of the "others". I also know the difference between 
lattice and structure. :)


Larry

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Re: Rietveld website cancelled ?

[Le Bail Armel]

OK, seems that the SDPD book preface looks unclear to some.

 

Western movies adepts well know that sentence :

"You see, in this world there's two kinds of people, my friend: those with 
loaded guns, and those who dig. You dig. .."

 

Similarly, there are two kinds of people, those believing that the sense of the 
words "structure determination" and


"structure refinement" are the same, and the others. You dig.


 

Best


 

Armel


 

 

 

 

> Message du 29/08/18 18:09
> De : "Larry Finger" 
> A : "Le Bail Armel" , Rietveld_L@ill.fr
> Copie à : 
> Objet : Re: Rietveld website cancelled ?
> 
> On 08/29/2018 04:15 AM, Le Bail Armel wrote:
> > Hi,
> > 
> > After the IUCr Monograph on Crystallography 13 (2002)
> > 
> > entitled "Stucture Determination from Powder Diffraction Data"
> > 
> > you may find in the preface :
> > 
> > "Although the Rietveld method of structure refinement from powder
> > 
> > diffraction data is often loosely considered to be synonymous with structure
> > 
> > determination, it is not. The Rietveld method only comes into play in the
> > 
> > final stage of the structure solution process when an approximate structural
> > 
> > model has been found."
> > 
> > WIF David, K Shankland, LB McCusker, C Baerlocher
> > 
> > A clear distinction having my complete agreement.
> > 
> > Armel
> 
> Armel,
> 
> Although the above statement may be generally true, I can provide a counter 
> example. In Max W. Schmidt, Larry W. Finger, Ross J. Angel, and Robert E. 
> Dinnabier, "Synthesis, crystal structure, and phase relations of AlSiO2OH, a 
> high pressure hydrous phase", American Mineralogist, V. 83, 881-888, 1998, we 
> only had a powder - no single crystals. From data measured at ESRF, we used 
> GSAS 
> to isolate the peaks of interest for the unknown phase, and used program 
> TREOR 
> to autoindex the unknown and identify the impurity phases. We then extracted 
> intensities using the LeBail method, and determined the structure using 
> direct 
> methods with program SIRPOW. The structure was then refined with GSAS. We 
> were 
> even able to locate the H atom from Fourier maps!
> 
> Even 20 years ago, it was possible to determine the structure from X-ray 
> powder 
> patterns.
> 
> Larry
> 
> 
>++
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Re: Rietveld website cancelled ?

[Peter Y. Zavalij]

It all depends on the definition. If/when we agree on the definition, there
is usually no points for further arguing.
Anyway we could call Relieved method a structure determination from powder
data as long as it does not included solving structure (or as David
elegantly put - true structural solution).
Peter

Peter Y. Zavalij
Director - X-ray Crystallographic Center
University of Maryland,
College Park, MD 20742



On Wed, Aug 29, 2018 at 12:38 PM David Elbert  wrote:

> Absolutely important that people understand that the Rietveld method is
> structure refinement and not solution, but as Larry points out sometimes
> you can get a more out of it if you’re clever… and have no other choice!
> Here’s a second example:
>
> Stubbs et al., 2010, Uranyl phosphate sheet reconstruction during
> dehydration of metatorbernite [Cu(UO2)2(PO4)2·8H2O], American
> Mineralogist 95 (8-9): 1132-1140 which is a bit of a brute-force approach
> to implying structures of some uranyl phosphates in a synchrotron heating
> experiment.  Joanne Stubbs sorted through known structures of related
> materials and used observed trends in refinements to select similar
> structures to further investigate.  Able to then postulate reasonable
> structures which then refined to the observed data and provided insight
> into this interesting group of materials.
>
> Not the standard way to employment of Rietveld Refinement and certainly
> not true structural solutions, but a smart, useful, and rather satisfying
> application nonetheless.
>
> Best-
> David
>
> David Elbert
> Hopkins Extreme Materials Institute
> Malone Hall
> Johns Hopkins University
> 3400 N. Charles St
> Baltimore, MD 21218
>
> (410) 516-5049
>
> elb...@jhu.edu
>
>
>
>
>
>
>
>
> On Aug 29, 2018, at 12:09 PM, Larry Finger 
> wrote:
>
> On 08/29/2018 04:15 AM, Le Bail Armel wrote:
>
> Hi,
> After the IUCr Monograph on Crystallography 13 (2002)
> entitled "Stucture Determination from Powder Diffraction Data"
> you may find in the preface :
> "Although the Rietveld method of structure refinement from powder
> diffraction data is often loosely considered to be synonymous with
> structure
> determination, it is not. The Rietveld method only comes into play in the
> final stage of the structure solution process when an approximate
> structural
> model has been found."
> WIF David, K Shankland, LB McCusker, C Baerlocher
> A clear distinction having my complete agreement.
> Armel
>
>
> Armel,
>
> Although the above statement may be generally true, I can provide a
> counter example. In Max W. Schmidt, Larry W. Finger, Ross J. Angel, and
> Robert E. Dinnabier, "Synthesis, crystal structure, and phase relations of
> AlSiO2OH, a high pressure hydrous phase", American Mineralogist, V. 83,
> 881-888, 1998, we only had a powder - no single crystals. From data
> measured at ESRF, we used GSAS to isolate the peaks of interest for the
> unknown phase, and used program TREOR to autoindex the unknown and identify
> the impurity phases. We then extracted intensities using the LeBail method,
> and determined the structure using direct methods with program SIRPOW. The
> structure was then refined with GSAS. We were even able to locate the H
> atom from Fourier maps!
>
> Even 20 years ago, it was possible to determine the structure from X-ray
> powder patterns.
>
> Larry
>
>
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  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/
> ++
>
>
> ++
> Please do NOT attach files to the whole list  >
> Send commands to  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/
> ++
>
>
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RE: Rietveld website cancelled ?

[Von Dreele, Robert B.]

Hi Armel,
A more extreme example was in Acta D56, 1549-1533 (2000) where a protein 
structure (a new insulin phase) was solved by rigid body Rietveld refinement 
from a synchrotron powder data set & subsequently confirmed by a single crystal 
analysis (see Acta Cryst. (2001). D57, 1091-1100). NB: this kind of thing has 
also happened more recently (see papers by Margiolaki, et al).
Bob Von Dreele

-Original Message-
From: rietveld_l-requ...@ill.fr  On Behalf Of Larry 
Finger
Sent: Wednesday, August 29, 2018 11:10 AM
To: Le Bail Armel ; Rietveld_L@ill.fr
Subject: Re: Rietveld website cancelled ?

On 08/29/2018 04:15 AM, Le Bail Armel wrote:
> Hi,
> 
> After the IUCr Monograph on Crystallography 13 (2002)
> 
> entitled "Stucture Determination from Powder Diffraction Data"
> 
> you may find in the preface :
> 
> "Although the Rietveld method of structure refinement from powder
> 
> diffraction data is often loosely considered to be synonymous with 
> structure
> 
> determination, it is not. The Rietveld method only comes into play in 
> the
> 
> final stage of the structure solution process when an approximate 
> structural
> 
> model has been found."
> 
> WIF David, K Shankland, LB McCusker, C Baerlocher
> 
> A clear distinction having my complete agreement.
> 
> Armel

Armel,

Although the above statement may be generally true, I can provide a counter 
example. In Max W. Schmidt, Larry W. Finger, Ross J. Angel, and Robert E. 
Dinnabier, "Synthesis, crystal structure, and phase relations of AlSiO2OH, a 
high pressure hydrous phase", American Mineralogist, V. 83, 881-888, 1998, we 
only had a powder - no single crystals. From data measured at ESRF, we used 
GSAS to isolate the peaks of interest for the unknown phase, and used program 
TREOR to autoindex the unknown and identify the impurity phases. We then 
extracted intensities using the LeBail method, and determined the structure 
using direct methods with program SIRPOW. The structure was then refined with 
GSAS. We were even able to locate the H atom from Fourier maps!

Even 20 years ago, it was possible to determine the structure from X-ray powder 
patterns.

Larry


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[no subject]

[Максим Молокеев]

Dear Colleagues,

I need your expert point of view on the complex problem associated with the 
thermal parameters.

Description:
New crystal structure contained Ba, Ca, K, P,O elements (with some Mn,Eu 
dopants) was solved and refined using Topas 4.2. The Checkcif tool found only a 
few Alert C, namely: Low ’MainMol’ Ueq as Compared to Neighbors of P1. The 
thermal parameters Biso of Ba ion are in the range of 1.52(8)-2.84(5) A^2, 
Biso(Ca)= 2.5(2)A^2, Biso(K) = 1.1(1) A^2, Biso(P)=1.52(6) A^2, O ions have 
3.2(1) A^2 (one parameter for all O ions). 
There are 15 independent ions in the asymmetric cell. The pattern was measured 
using CuKa in the range of 5-140 deg. Max. Intensity ~200.000 Cps.

The Problem:
The Reviewer wrote that the suggested crystal structure was less than 
satisfactory because Biso should be less that 0.7A^2 for cations and less than 
2A^2 for oxygens.

The similar published structure with the same problem:
I have found the cif-file of the similar structure Ba2CaNa3(PO4)3, which was 
solved/refined using single crystal method, that Biso(Ba) are in the range of 
1.58-1.75 A^2 which is much bigger than 0.7 A^2 and the Biso(O) values vary in 
the range of 1.42-4.3 A^2.

So, I have the questions:
-Where can I get the reliable information about the trustful range for thermal 
parameters? 
-Who and why decides to involve these maximal values 0.7 A^2 for heavy ions and 
2A^2 for oxygen ions. Maybe do you know the relevant manuscript?
-Whether the Ba2CaNa3(PO4)3 structure [Kim, M., Kobayashi, M., Kato, H., 
Yamane, H., Sato, Y., & Kakihana, M. (2015). Dalton Transactions, 44(4), 
1900-1904] with so "big" thermal parameter also was solved/refined using single 
crystal experiment less than satisfactory?

I think the problem will arise several times in the future and answers will be 
a great help to many subscribers here.
Sorry for long text.

Best wishes,
Maxim


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Re: Rietveld website cancelled ?

[Larry Finger]

On 08/29/2018 04:15 AM, Le Bail Armel wrote:

Hi,

After the IUCr Monograph on Crystallography 13 (2002)

entitled "Stucture Determination from Powder Diffraction Data"

you may find in the preface :

"Although the Rietveld method of structure refinement from powder

diffraction data is often loosely considered to be synonymous with structure

determination, it is not. The Rietveld method only comes into play in the

final stage of the structure solution process when an approximate structural

model has been found."

WIF David, K Shankland, LB McCusker, C Baerlocher

A clear distinction having my complete agreement.

Armel


Armel,

Although the above statement may be generally true, I can provide a counter 
example. In Max W. Schmidt, Larry W. Finger, Ross J. Angel, and Robert E. 
Dinnabier, "Synthesis, crystal structure, and phase relations of AlSiO2OH, a 
high pressure hydrous phase", American Mineralogist, V. 83, 881-888, 1998, we 
only had a powder - no single crystals. From data measured at ESRF, we used GSAS 
to isolate the peaks of interest for the unknown phase, and used program TREOR 
to autoindex the unknown and identify the impurity phases. We then extracted 
intensities using the LeBail method, and determined the structure using direct 
methods with program SIRPOW. The structure was then refined with GSAS. We were 
even able to locate the H atom from Fourier maps!


Even 20 years ago, it was possible to determine the structure from X-ray powder 
patterns.


Larry


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Re: Rietveld website cancelled ?

[Le Bail Armel]

 

>Very few citations though;

 

The fact is that you don't cite this couple of examples in your own list of 
selected publications :

http://hewat.net/science/

If you find them of poor interest, the World follows you.

 

Armel

 

PS - A positive search-match (using the COD) signifies that the structure is 
already determined (not always if you use ICDD), then if you wish, you may 
refine it by the Rietveld method

 

 

> Message du 29/08/18 12:35
> De : "Alan Hewat" 
> A : "Armel Le Bail" 
> Copie à : "rietveld_l@ill.fr" 
> Objet : Re: Rietveld website cancelled ?
> 
>
> A clear distinction having my complete agreement. (Armel)
Ouf. Nous sommes d'accord enfin :-) For Armel, here are a couple of examples of 
automatic indexing, search-match and structure DETERMINATION from neutron 
powder data. Very few citations though; crystallographers largely ignored 
neutron powder diffraction before 1987 and Hi-Tc :-)


__
>
   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE 
+33.476.98.41.68
>         http://www.NeutronOptics.com/hewat
> __






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Re: Rietveld website cancelled ?

[Alan Hewat]

> A clear distinction having my complete agreement. (Armel)
Ouf. Nous sommes d'accord enfin :-) For Armel, here are a couple of examples

of automatic indexing, search-match and structure DETERMINATION from
neutron powder data. Very few citations though; crystallographers largely
ignored neutron powder diffraction before 1987 and Hi-Tc :-)
__
*   Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
 +33.476.98.41.68
http://www.NeutronOptics.com/hewat
__
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RE: Rietveld website cancelled ?

[Le Bail Armel]

Hi,

 

After the IUCr Monograph on Crystallography 13 (2002)

entitled "Stucture Determination from Powder Diffraction Data"

you may find in the preface :

"Although the Rietveld method of structure refinement from powder

diffraction data is often loosely considered to be synonymous with structure

determination, it is not. The Rietveld method only comes into play in the

final stage of the structure solution process when an approximate structural

model has been found."

WIF David, K Shankland, LB McCusker, C Baerlocher

 

A clear distinction having my complete agreement.

 

Armel

http://www.cristal.org/CAC-XX/maze.jpg

http://www.cristal.org/CAC-XX/Rietveld.ppt

 

 

> Message du 29/08/18 10:14
> De : "May, Frank" 
> A : "Alan Hewat" , "rietveld_l@ill.fr" 
> Copie à : 
> Objet : RE: Rietveld website cancelled ?
> 
> To all:
> 
> Initially I sent this to Alan who suggested I open discussion to the entire 
> community. I've posted similar in past years and have been FLAMED. Please 
> keep it civil. ;-)
> =
> As a long time practitioner of powder XRD (since 1972) I was there when the 
> superconductor craze hit in the mid-1980s. At that time it was recognized the 
> Rietveld Method was useful only for REFINING structures which were generally 
> accepted from single crystal x-ray analysis.
> 
> The http://www.cristal.org/rietv025/ link says the method "[allows] an 
> accurate determination of the structure." I take that statement to mean no 
> model is required; Rietveld Analysis can determine structure without 
> preconceived model.
> 
> Thanks for reading.
> 
> Blessings from toasty and warm St. Louis, MO.
> 
> Frank May
> Research Investigator
> University of Missouri-St. Louis
> 
> formerly at Monsanto Company (which recently became part of 
> BAYER)++
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eg: HELP as the subject with no body text
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> ++
> 
>++
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RE: Rietveld website cancelled ?

[May, Frank]

To all:

Initially I sent this to Alan who suggested I open discussion to the entire 
community.  I've posted similar in past years and have been FLAMED.  Please 
keep it civil.  ;-)
=
As a long time practitioner of powder XRD (since 1972) I was there when the 
superconductor craze hit in the mid-1980s.  At that time it was recognized the 
Rietveld Method was useful only for REFINING structures which were generally 
accepted from single crystal x-ray analysis.

The http://www.cristal.org/rietv025/ link says the method "[allows] an accurate 
determination of the structure."  I take that statement to mean no model is 
required; Rietveld Analysis can determine structure without preconceived model.

Thanks for reading.

Blessings from toasty and warm St. Louis, MO.

Frank May
Research Investigator
University of Missouri-St. Louis

formerly at Monsanto Company (which recently became part of BAYER)++
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