Re: GSAS-II - indexing TOF data

Hi Alex I think conograph does well for tof. Best Jon On April 13, 2020 8:24:55 PM GMT+02:00, Alexandros Lappas wrote: >Dear colleagues, > > > >We are working on some neutron time-of-flight (TOF) data and attempt to >index them within GSAS-II. > > > >As the low-angle detector banks contain

Re: Asymmetry peak shape difference between (pellet/powder)

Hello, In the photo, the pellet is black and the powder is white. Why is that? Best Jon On December 8, 2017 3:35:20 PM GMT+01:00, "François Goutenoire" wrote: >Dear Rietveld users, > >We observe an unusual asymmetric peak shape on pellet and not when the

Re: TOPAS Macro Language (peak shape broadening macros)

Hi Alan, In the limiting case of orienting all crystals in 3D you get a mosaic single crystal (e.g. [1], or using an XFEL to measure 1 at a time). Then the refined the crystal structure has somewhat better accuracy than with a 1D Rietveld fit. Perhaps not the most popular idea for this

Re: regress in crystallographic good practices and knowledge

Dear Kurt, You can peaksearch the images with any number of packages and then look at the extracted spot positions. The stuff we wrote lives at http://sourceforge.net/projects/fable/ and it is normally used to fit grain-by-grain strain tensors. If you can isolate the spots you do indeed get a

Re: Delta ferrite by xrd

On 08/08/2013 18:04, led15 wrote: Is possible confirm the presence of delta ferrite in steel by xrd. Yes: http://dx.doi.org/10.1007/s11661-010-0371-7 ++ Please do NOT attach files to the whole list alan.he...@neutronoptics.com Send

Re: [sdpd] Re: Are restraints as good as observations ?

On 31/07/2013 20:19, Brian Toby wrote: To perform R-free with powder data, one must excise multiple complete peaks from the pattern, say a few sections making up 10-20% of pattern. Hi Brian, It is not so bad, you only need to throw in some peak intensities as variables (a partial Pawley).

Re: Negative Uiso in GSAS

I can't resist adding one more to Mike's excellent list: 5. When peaks overlap strongly it becomes difficult to determine the background level. Negative Uiso is a consequence of the background refining to a value which is too low, especially where the peaks are most dense in the pattern

Re: Mask for Fit2d

Just use mask polygon and draw a little triangle inside the pixel you want to mask. It helps to zoom in first. (Usually it is easier to find the hot pixels with a threshold mask anyway). Best, Jon Yang, Ling wrote: Hi, Does anyone know how to mask single pixel in Fit2d? I found it

Re: UVW - how to avoid negative widths?

According to Caglioti relation, the dimensions of U,V,W are as (angle)^2. Quick question - does anyone have a trick to stop the Cagliotti formula going negative? Prodd currently has a habit of bugging out on a sqrt(negative) and I'm wondering how other folks worked around that, or if I've

Re: UVW - how to avoid negative widths?

Alan Hewat wrote: Jon Wright said: Quick question - does anyone have a trick to stop the Cagliotti formula going negative? This can happen if the resolution is relatively flat, so that there is no well defined minimum. Seems to be the problem - also rather close to zero anyway

Re: How to determine the crystalline system

Alan Hewat wrote: ... your name appears as ½¨²¨Áº The problem is your mail reader, thunderbird displays some chinese characters. Liang's mail correctly uses a MIME encoded word as the ascii string: =?GB2312?B?vaiyqMG6?= Which means character set GB2312 (chinese), Base64 encoding, and

Re: cRs

Olga Smirnova wrote: Did anyone try to calculate simple mean deviance and compare with popular R factors? OS For simple mean deviance do you mean like in: http://en.wikipedia.org/wiki/Deviance_(statistics) Seems we normally call that chi^2. If that's what you meant, then yes, people do

Re: cRs

Dear Olga, As you've noticed, the Rietveld R-factors tell you how well you fit the pattern, but don't tell you how well you fit the peaks. There is a correlated intensities R-factor which follows from the methods outlined in: J. Appl. Cryst. (2004). 37, 621-628[

Re: scattering factor for B+3

Out of curiousity, I'm wondering, do many people use ionic scattering factors instead atomic ones for Rietveld refinement? Cheers, Jon Lubomir Smrcok wrote: Just one question : have you asked your supervisor before sending such a mail ? Though I understand your position it seems that you

TotalCryst workshop, Grenoble, 1-3 April 2009

You are warmly invited to attend a 3-day Workshop in Grenoble, which aims at explaining the TotalCryst methods and demonstrating the FABLE software package. http://www.esrf.fr/events/conferences/TotalCryst/TotalCryst/ Please bring this to the attention of your colleagues. Registration is open

Re: Bragg-Brentano vs. parallel beam

Markus Valkeapää wrote: Any comments on these two different geometries here on Rietveld list? It depends on the sample? Reflection geometry helps when there is a lot of absorbtion. Jon

Re: calculating f' and f''

Try this: ftp://ftp.ccp4.ac.uk/ccp4/6.0.2/source/chooch-5.0.2-src.tar.gz Best, Jon Jean-Marc Joubert wrote: Hello, I am looking for a program able to calculate f' and f'' from absorption data for a resonnant diffraction experiment. I know that CHOOCH program was able to do that. This

Re: Portable XRD

Hi, If you have the usual environment variables set : GSAS=c:\gsas PATH=...;c:\gsas\exe PGPLOT_FONT=c:\gsas\pgl\grfont.dat then it should all run from a dos prompt (run - cmd or command.com). Or at least, you can type expedt, powpref and genles etc and the programs run and even deal with

Re: [sdpd] Re: Background Subtractions / 2D image plate

in Bckgrnd Subtr.zip), I'll send then to you directly. --- In [EMAIL PROTECTED] mailto:sdpd%40yahoogroups.com, Jon Wright [EMAIL PROTECTED] wrote: Hello Yetta, If you can also add a jpg of the image too, it would show whether there is a high background in the actual data too. Otherwise try

Re: WARNING: Posting large attachments on the Rietveld list

We have also limited the size of Rietveld list messages to 0.5 Kbytes 0.5 KBytes is only 512 characters? I would h8 2 c text message style language as a consequence :-) Best, Jon

Re: Fullprof setup Linux

William, The ELF usually means it is the equivalent of a .exe file? Try: chmod a+x setup_fullprof_suite ; ./setup_fullprof_suite Something came up on the list a while ago about a upx issue. You previously needed something like: $ sudo apt-get install upx-ucl $ upx -d fp2k But perhaps

Re: advice on new powder diffractometer

Alan Hewat wrote: Many theoretical arguments about signal/noise forget that the experimentalist has a finite time to collect his data :-) The finite time to analyse and publish can also be rate limiting! In this respect a high background is a fine addition to any instrument; it gives a much

Re: advice on new powder diffractometer

Kurt Leinenweber wrote: ... with wRp of 25% and crystallographic R also near 25% .. Maybe the background is too low :-? Jon

Re: GSAS total beginner questions

Works for me. Just fill out a BANK line with FXY or FXYE as described in the manual :-) Cheers, Jon [EMAIL PROTECTED] wrote: Isn't GSAS able to handle XY data?? Cheers Matthew Matthew Rowles CSIRO Minerals Box 312 Clayton South, Victoria AUSTRALIA 3169 Ph: +61 3

Re: Automated phase matching?

Yetta Porter wrote: Hello all, I am interested in finding software that can convert 2D diffraction rings into 1D diffraction patterns AND allow phase/pattern matching using the ICDD's PDF database. Currently, I am using Fit2D to convert my rings to patterns and then Match! to phase match my

Open Access Articles: 60 years of Acta Crystallographica and the IUCr

Hello Everyone, Some reviews have just come out in the first 2008 issue of Acta A: 60 years of Acta Crystallographica and the IUCr: http://journals.iucr.org/a/issues/2008/01/00/issconts.html Start citing now for a nicely skewed impact factor in a few years time :-) Happy Christmas, Jon

Re: X-ray scattering contrast Fe/Cu

Just a quick plug for a program called chooch which does a very nice job of calculating f' and f from an edge scan, see: http://www.gwyndafevans.co.uk/chooch.html For Fe/Cu then neutrons may help. Cheers, Jon [...] Each edge to be used is recorded, this allow to calculate using

Re: Absolute structure from powder data?

Did anyone look into the effects of using circularly polarised x-rays? Just wondering... Jon Larry Finger wrote: Franz Werner wrote: Dear Rietvelders Is it in principle impossible to determine the absolute structure from powder data due to reflection overlap or is there a way via multiple

Re: gnuplot help regarding

Easiest is to click on the top corner of the plot window and select options copy to clipboard. Or directly write to gif via: gnuplot set terminal gif Terminal type set to 'gif' Options are 'small size 640,480 ' gnuplot set output test.gif gnuplot plot sin(x) gnuplot set terminal win Terminal

Re: peaks splitting

Hi everyone, Three responses saying it might be a lower spacegroup? I wonder if the emperors have their clothes on today? (006) reflections can't split in R-3c as they only have a multiplicity of 2 in the first place (0,0,6 and 0,0,-6). You were lucky enough to split (00l) which rules out

[Fwd: [ccp4bb] Nature policy update regarding source code]

Hi Everyone; Just in case you don't follow ccp4bb or nature methods: http://www.nature.com/nmeth/journal/v4/n3/full/nmeth0307-189.html I thought that some of you might be interested that the journal Nature has clarified the publication requirements regarding source code accessibility. It is

Re: [Fwd: [ccp4bb] Nature policy update regarding source code]

AlanCoelho wrote: Not sure what to make of all this Jon Don't shoot the messenger, I was surprised enough by it to forward it to the list. I guess they imply if you want to keep all implementation details secret you should be patenting instead of publishing? (Patents seems to be free

Re: GSAS: interpretation of strain broadening

Let's say one gets a value of 0.1% strain. = width of the distribution of cell parameters in the sample But on the other hand there are also the unit cell sigmas. = error bar on the average value of the cell parameters How can one visualise this? There is a distribution of cell

Re: GSAS ESD/STD conversion

Brian H. Toby wrote: I am trying to convert a GSAS ESD file to a GSAS STD file BTW, I would be surprised if FullProf does not have a way to input intensities with uncertainties rather than assuming intensities are counts. Indeed it does! INSTRM=10 is x, y, sigma format for fullprof where

Re: How to prepare intensity and hkl files needed by SHELXTL-97

I've attached a python script below which will convert a gsas rfl file into shelx hklf 4 format - it assumes there is no peak overlap at all, so it is *not* hklf 5 format and *not* suitable for refinement! After installing python from www.python.org and copying the script into your working

Re: fundamental parameters approach X'celerator

I did some tests on the profile of the first diffraction peak of LaB6, where I added a secondary soller angle, since I used secondary soller slits, and I added also the parameter for the horizontal divergence in the equitorial plane. Finally I added a crystallite-size parameter CS_L. I did

Re: fundamental parameters approach X'celerator

Its best to use the terms axial plane and horizontal plane to avoid confusion. Alan, I'm confused! What do you mean by those terms? I thought axial divergence was beam hits different points along the two theta axis - is that a misconception? Last point, what do you mean by vertical

Re: Level of Preferred Orientation

Dear Bhuv pattern and I have corrected possible graininess with spherical [...] The data I have collected is on a image plate (only one frame). Not sure I understand? If you have a 2D image showing powder rings then you should have some very good ideas about the level of granularity or texture

Re: Change format

Brian Toby wrote: If the numbers are real values then they are not counts. They may be counts per second or something else. One needs to have uncertainty estimates for these intensities before one can do a meaningful Rietveld refinement (with any code). Following the above procedure, by

Re: Questions about the asymmetry correction

Xianqin, How did you calibrate the sample detector distance? For reliable absolute cell parameters it is very difficult to get good data with an area detector. One approach is to mix a standard material into the sample. As a gross approximation for small angles (in radians): sin(theta) ~ theta

Re: TOPAS-Academic

Alan, The planned plugin architecture sounds interesting. How concrete are the plans? I'm interested in auto-generation of restraints for proteins and fourier mapping at the moment... Regards, Jon alan coelho wrote: Dear all, An academic version of BRUKER-AXS TOPAS is now available to

Re: Rietveld refinement and PDF refinement ?

Well, that is an old chestnut that Cooper and Rollet used to oppose to Rietveld refinement. I think Rollet eventually agreed that Rietveld was the better method. Has Bill really gone back on that ? The difference between the two approaches are just an interchange of the order of summations

Re: fundamental parameters approach

Is the fundamental parameter approach better than mathematical approach used in most of the Rietveld refinement programs? Perhaps someone is about to explain the difference is between fundamental parameters and anything else? I used to think it might mean convoluting something which was

Re: GSAS informations

... to answer to your (too) long questions. May be later, OK? Going back to this quartics versus ellipsoids peak broadening stuff, maybe I can summarise: Why should the distribution of lattice parameters (=strain) in a sample match the crystallographic symmetry? If the sample has random,

Re: GSAS informations

Not violating symmetry restrictions you may either have the sphere with the terms 11=22=33 and 12=13=23=0 or something else allowing the 12=13=23 terms to be equal but different from 0. These two possibilities are all you can do in cubic symmetry with h,k,l permutable. If I am not wrong. The

Re: GSAS informations

Nicolae Popa wrote: the condition to not violate some elementary principles, in particular, here, the invariance to symmetry. Dear Prof Popa, I had been meaning to implement the quartic form for peak width in a refinement program for some time, but did not figure out how to generate the

Choosing origins

I am amazed by the flow of miss information that flows on this list whenever an apparent problem with a space group comes up. I asked a related question on sci.techniques.xtallography a few weeks ago, but have yet to hear anything, misinformation or otherwise. If anyone here can give me some

Re: Magnetic Form Factor of Ru+4

Ozhan Unverdi wrote: Could someone give me the magnetic scattering factors of Ru+4 please? www.google.com searching for Ru4+ magnetic form factor gives 17 results. One of them is Sidis et al, Evidence for Incommensurate Spin Fluctuations in Sr2RuO4, Phys. Rev. Lett (1999) 83, 3320. In

RE: Riet_L: Scale factor in Rietveld (with a question for Bob and Juan)

Paolo, On Fri, 15 Sep 2000, Radaelli, PG (Paolo) wrote: . Finally, here is a question for Bob and Juan. To me, it would be much more natural to remove Vo from the scale factor, that is to redefine a new S' so that Y=S'*L*A*E*|F|^2/Vo^2 and S'=K*Ltot*f This way, the scale factor

Re: GSAS and CYCLIC refeinements ?

Alex, There's something below which might help you. You'd need to set up a refinement with a .exp file and a .raw file with the same root name (eg fit.raw and fit.exp). The batch file then takes two arguments, the data file name (eg run1.raw) and the root of name of the .exp file (eg. fit for

Fitting lorentzian tails in GSAS

low angle asymmetry correction) would be also be appreciated. Thanks in advance, Jon Wright Dept. of Chemistry, Lensfield Road, Cambridge, CB2 1EW Phone-Office 01223 (3)36396; Lab 01223 (3)36305; Home 01223 462024

Re: Asymmetry

Asymmetry is discussed in: J.Appl.Cryst (1984) 17, p.47 - van Laar Yelon (+ ref's therein) The above method is implemented in: J.Appl.Cryst (1994) 27, p.892 - Finger, Cox Jephcoat. and source code for this peakshape is available. (They also talk about secondary monochromators). Hope

Re: Absorption GSAS and TOF Instruments

on is only a problem when the peaks disappear. Hope this helps, Jon Wright PS: Can anyone tell me if sigma_abs goes as 1/v for Gd? Dept. of Chemistry, Lensfield Road, Cambridge, CB2 1EW Phone-Office 0122

Re: Understatement of the year..so far

On Fri, 7 Jan 2000, Armel Le Bail wrote: 15mn for checking a crystallography set is about my performance too. Just out of interest, how long does it take people to pick up the error in entry number 17280, attached below. It's just a cell transformation from the cubic spinel [a-(a+b)/2,

Cell constraints question

matrix rather than the real space unit cell parameters? I haven't picked up yet on why the derivatives cannot be converted from w.r.t A* etc to w.r.t a etc. Is it just a time saving? Thanks Jon Wright Dept

RE: As sent to the neutron mailing list

... not at all for magnetism, ... Ahem, magnetism - resolution is very useful, in certain (rare) cases. I guess that magnetic structures are not Armel's primary interest but in at least one case resolution was essential. (FeAsO4 from IRIS (TOF neutron) dataset, J.Phys:Condens.Matter 11 (1999)

Re: Bond length and angle ESDs

On Thu, 23 Sep 1999, Ed Cussen wrote: We're forced to use CCSL for the superior peak shape description and so simply changing refinement program is not an option. I'm sure that this problem must have been encountered before and I'm suprised that there's not a 'standard' solution to it.

Re: RIET: Are Spherical Harmonics for Preferred OrientationCorrection Evil?

On Thu, 16 Sep 1999, Dr.Joerg Bergmann wrote: (high systematic error, bad difference plot, but low e.s.d.'s) (low systematic error, good difference plot, but high e.s.d.'s). Apologies for diving off onto the general case, but does this make sense? You improve your model and the quality of

RE: Combined neutron/x-ray refinements

, sometimes it's the quickest way to learn. Jon Wright PS: Sorry to pick at your comments Paolo, it's a shame I'm not at RAL at the moment. Could have discussed it out over a coffee...

RE: Combined neutron/x-ray refinements

in the x-ray model :) Maybe not if one looks on the x-ray refinement as fitting of the electron density function, rather than the nuclear positions. For bonding studies it is the differences which are of interest! Jon Wright. PS: Any offers other than GSAS and multipattern fullprof for actually

Re: Combined neutron/x-ray refinements

ta version. It appears you can assign the statistical weight to each pattern, and in the example x-rays and neutrons are weighted equally. I'm wondering what the best choice is. Each observation comes with a statistical weight from the experiment? Isn't it a sin to alter that?

Re: Graphics

ld try MI/X. The URL to download MI/X from MicroImages' is http://www.microimages.com/ in the "Free Downloads" section. Hope this helps, Jon Wright On Tue, 30 Mar 1999, Hongwu Xu wrote: Hi, Everyone, We have some neutron diffraction data collected and stored in the VAX co