September 2011 - Ifeffit - millenia.cars.aps.anl.gov

Re: [Ifeffit] Negative Sigma^2
by pierre.lecante＠cemes.fr 14 Sep '11

14 Sep '11

one big issue is if your frequency terms are right when the amplitude ones are wrong, i.e. if you have computed and experimental chi functions reasonnably in phase while keep a not too high deltaE0 value; if so, as Scott said it sounds like a correlation between amplitude terms, which is fairly common; maybe an incorrect amplitude reduction factor, but more likely something wrong in the model: neighbours too light, or with a wrong multiplicity; if not, even worse and hard to say; my two cents, Pierre ifeffit-request(a)millenia.cars.aps.anl.gov a écrit : > Send Ifeffit mailing list submissions to > ifeffit(a)millenia.cars.aps.anl.gov > > To subscribe or unsubscribe via the World Wide Web, visit > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > or, via email, send a message with subject or body 'help' to > ifeffit-request(a)millenia.cars.aps.anl.gov > > You can reach the person managing the list at > ifeffit-owner(a)millenia.cars.aps.anl.gov > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Ifeffit digest..." > > > Today's Topics: > > 1. Negative Sigma^2 (Palomino, Robert) > 2. Re: Negative Sigma^2 (Scott Calvin) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 13 Sep 2011 13:32:46 -0400 > From: "Palomino, Robert" <rpalomino(a)bnl.gov> > To: <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: [Ifeffit] Negative Sigma^2 > Message-ID: > <B32CD18BE9D42745B75847F981879A3602D1BF05(a)exchangemb3.bnl.gov> > Content-Type: text/plain; charset="us-ascii" > > I am trying to fit data I recently collected and occasionally I am > getting negative sigma squared values. Could anyone tell me what this is > indicative of: am I using the wrong model or are my initial guesses of > some parameters way off? > > > > Robert > >

1 0

Negative Sigma^2
by Palomino, Robert 13 Sep '11

13 Sep '11

I am trying to fit data I recently collected and occasionally I am getting negative sigma squared values. Could anyone tell me what this is indicative of: am I using the wrong model or are my initial guesses of some parameters way off? Robert

2 1

Re: [Ifeffit] Ifeffit Digest, Vol 103, Issue 9
by Mikutta Christian 11 Sep '11

11 Sep '11

Hi Marc, Forgot another illuminative paper: Van Schaik J.W.J. et al. (2008) EXAFS study on the reactions between iron and fulvic acid in acid aqeous solutions. Environ. Sci. Technol. 42, 2367-2373. Cheers, C. -----Original Message----- From: ifeffit-bounces(a)millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On Behalf Of ifeffit-request(a)millenia.cars.aps.anl.gov Sent: Thursday, September 08, 2011 7:00 PM To: ifeffit(a)millenia.cars.aps.anl.gov Subject: Ifeffit Digest, Vol 103, Issue 9 Send Ifeffit mailing list submissions to ifeffit(a)millenia.cars.aps.anl.gov To subscribe or unsubscribe via the World Wide Web, visit http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit or, via email, send a message with subject or body 'help' to ifeffit-request(a)millenia.cars.aps.anl.gov You can reach the person managing the list at ifeffit-owner(a)millenia.cars.aps.anl.gov When replying, please edit your Subject line so it is more specific than "Re: Contents of Ifeffit digest..." Today's Topics: 1. Re: Fitting on Athena (Niken Wijaya) 2. Re: Fitting on Athena (Bruce Ravel) 3. Re: Fitting on Athena (Matt Newville) ---------------------------------------------------------------------- Message: 1 Date: Thu, 08 Sep 2011 09:52:38 +1000 From: Niken Wijaya <niken.wijaya(a)monash.edu> To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> Subject: Re: [Ifeffit] Fitting on Athena Message-ID: <4E6803C6.9070407(a)monash.edu> Content-Type: text/plain; charset="iso-8859-15"; Format="flowed" On 7/09/2011 7:24 AM, Bruce Ravel wrote: > On Sunday, September 04, 2011 08:52:30 pm Niken Wijaya wrote: >> 1. As you can see on the figure (i.e. filename: ifeffitlist-sample1 >> fitting), the intensity of the fitting spectra is higher than the >> actual sample. This is I believe due to the higher intensity of the >> individual standard compounds when compared to the spectra of my samples (i.e. >> filename: ifeffitlist-intensity). This is the case for every fitting >> I did for my sample so I am just not sure with the fitting results. > Well, there are a lot of problems contributing to your confusion. > > One thing that probably doesn't help, but which certainly isn't the > central problem, is that you have extremely large values for the > y-axis offset parameter of several of the standards. This makes it > difficult to plot normalized spectra in an unconfusing way. > > Your central problem is that, for most of the data groups, the values > of parameters for the pre-edge and normalization lines are not well > chosen. It would seem that you trusted the default values without > checking them. See > > > http://cars9.uchicago.edu/~ravel/software/doc/Athena/html/bkg/norm.htm > l > > In your case, the default values resulted in unusably short ranges for > thepre-edge line or the post-edge line or both. The moral of this > story is to plot the data with its pre- and post-edge lines to verify > that the values result in sensible normalization. See > > > http://cars9.uchicago.edu/~ravel/software/doc/Athena/html/plot/tabs.ht > ml > > You also had a problem that some of your data were somehow imported as > normalized mu(E) rather than as mu(E) or xanes(E). See > > > http://cars9.uchicago.edu/~ravel/software/doc/Athena/html/import/colum > ns.html#datatypesandenergyunits > > This is usually not a good idea as it tells Athena that your data are > already reliably normalized and should not be further processed. > Those data, however, were not unit edge-step normalized, which is what > the LCF utility requires. The way to fix that in an existing Athena > project file is explained just a little further down on that same > page. > > Once I fixed the datatype for all of your groups and performed a > sensible normalization for your data, I got the LCF fit shown in the > attached image. Not great, but not the ridiculous result you were > getting with so many things done wrongly in your project file. > > I think that the underlying problem is that you expected Athena to > magically do the right thing with your data without verifying its > results. Or, perhaps, you plowed forward without fully understanding > how to use the program. The documentation isn't exactly exciting > reading, but it doesn't completely suck. You might want to bookmark > its URL. > > >> 2. If we see figure "ifeffitlist-sample39", we can see that the >> spectra has different slopes on the pre and post-edge region. When I >> used MBACK for background removal, the normalized spectra is weird, >> illustrated in "sample39-fig-norm.pdf". What is the best way to fix >> this issue? I have >> 5 samples with this feature that I cannot process due to the weird >> normalized spectra. > Well, MBACk isn't my thing, so I can only comment on it in general > terms. I suspect that you would get better results if you severely > truncated your data, say from about 2455 to 2515. Something wonky > happens in that spectrum at the beginning and the end. I suspect that > MBACK is having trouble figuring out what part of the data is actually > the edge step. > >> 3. Regarding the self-absorption correction, I was not aware that >> Athena has this function. I will have a look at the manual again. >> Thank you for letting me know. > > http://cars9.uchicago.edu/~ravel/software/doc/Athena/html/process/sa.h > tml > > Again, not exciting ... doesn't suck ... bookmark. > > Here's a talk I gave at the University of Ghent last January on the > topic of self-absortion corrections. It may be of some help to you: > > http://cars9.uchicago.edu/~ravel/misc/selfabs.pdf > >> 4. With the 3rd derivative spectrum, I did indeed derive it from the >> normalized values. As you can see from the file I attached earlier, >> from the experts points of view, do you think I should go on with the >> Nth derivative spectra or due to the very low signal-to-noise ratio >> of the spectra, I should just focus on the absorption spectra? > I don't really have an opinion one way or the other about the 3rd > derivative. The folks from Stanford and CLS who do a lot of sulfur > work have made extensive use of the 3rd derivative and they are really > smart people. I haven't done a lot of S work in my own career and > none of Athena's users have ever asked for a 3rd derivative option, so > Athena doesn't currently do that. > > B > > PS: Doesn't it just blow your mind how there is a strong correlation > between quality and clarity of the question and specificity of the > answer? Amazing...! > > > > > _______________________________________________ > Ifeffit mailing list > Ifeffit(a)millenia.cars.aps.anl.gov > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Hi Bruce, I think I have to clarify that I used MBACK to do the normalization instead of ATHENA. This might as well explain why I got such a high value of y-axis offset, why you think I did not choose the right parameters for the "pre-edge" and "normalization range" and also why I imported the data as normalized mu(E) rather than mu(E). As mentioned in the manual, doing normalization in Athena is very subjective, tiny difference in the point chosen for both the "pre-edge region" and "normalization range" will result in different normalized spectra. Due to lack of experience in processing XAFS spectra and noisy spectra obtained, I was planning to eliminate this problem by using MBACK. My initial plan was to combine the benefit I can get from both ATHENA and MBACK. So, I did the normalization using MBACK, then do the self-absorption correction and fit the normalized spectra in ATHENA. However, looking at your comment, LCF in ATHENA requires edge-step normalization, by saying that, does it mean that I cannot normalized my spectra using MBACK then fit them in ATHENA? Thanks, Niken

1 0

XAFS of poly-metals contaminated soil samples
by Xia Bing 09 Sep '11

09 Sep '11

Dear members of the mailing list: This year we have applied the synchrotron radiation and get the chance to Beijing Synchrotron Radiation Facility at beamline 1W1B-XAFS. It is the first time to use this equipment to measure our samples. We communicate with the beamline staff for some guideline and help, but they also do not have much experience on soil samples. Would you like give us some suggestions? If you could, can you supply me some resources like sample preparation or others? Now I try to use synchrotron radiation to elucidate some phenomenons of heavy metals in mining area soil. In my soil sample, the Zn is about 498ppm and the Cu is about 562ppm, the first step I focus on Zn but the copper concentration is higher than Cu. Will copper interfere zinc If I use XAFS to measure the Zn? I plan to use fluorescence detection. The Fe in the sample is at high concentrations (85g/kg), from some literature that might be an issue. Would you like to give me some suggestions in the sample preparation and measurement? Table 1. Characterization of the soil (mean ± SD, n = 3) > > TOC > > g·kg-1 > > TN g·kg-1 > > Available phosphorus > > mg·kg-1 > > Available potassium > > mg·kg-1 > > CEC > > cmol·kg-1 > > Trace metals mg·kg-1 > > Pb > > Zn > > Cu > > Cd > > Mine soil > > 3.69 > > 0.16 > > 0.9 > > 4.1 > > 5.27 > > 1368.2±244.76 > > 497.74±90.27 > > 562.2±94.36 > > 6.48±0.36 > *Not detected Thank you very much. Best Regards Xia Bing -- Department of Environmental Engineering, Room D-614, 6/F, Geography and Environmental Sciences Building, Sun Yat-sen University, Guangzhou, Guangdong, 510275 Cellphone: +86 150 1301 6565 Personal Website:http://sweetblues.cn

4 3

Fwd: Re: XAFS and feffit
by Bruce Ravel 09 Sep '11

09 Sep '11

Hi everyone, This fellow clearly did not take my hint that he should ask his question on the Ifeffit mailing list, so I am taking the liberty of forwarding his questions along. As for his first question: http://cars9.uchicago.edu/ifeffit/FAQ/RunningFeff#crystal The second question is rather too broad and open ended for me to know what to do with it, but perhaps someone else will want to take a stab. B ---------- Forwarded Message ---------- Subject: Re: XAFS and feffit Date: Friday, September 09, 2011, 08:53:12 am From: samrath ninama <samrathn(a)gmail.com> To: Bruce Ravel <bravel(a)bnl.gov> Hello Sir, I have some question about Artemis Software. 1.How can we get crystal structure's file for operating this software. 2.suppose we have doped ferrites with transition metal so what is required doping % of Cu/Co/Ni/Ti in all samples %. please give me the answer any way as soon as possible. SAMRATH NINAMA (EXAFS Reaearch) SOP, DAVV ,INDORE [MP],INDIA On Mon, Jul 25, 2011 at 5:39 AM, Bruce Ravel <bravel(a)bnl.gov> wrote: > > http://cars9.uchicago.edu/ifeffit/BruceRavel/FormLetters/HelpRequest > > > > On Sunday, July 24, 2011 07:51:05 am you wrote: > > Hello sir, > > > > My self *Samrath Ninama* Research Scholar SOP,DAVV ,*Indore* [mp] > > *INDIA*.My field of work is related to XAFS of some transition metal > > comlexes and feffit data analysis.I was attending *AWX 2011* ASEAN > > WORKSHOP ON X-RAY ABSORPTION SPECTROSCOPY ON 20-22 JUNE 2011 held AT > > *NAKHON RATCHASIMA ,THAILAND**,at There I was also meet with Dr.Matt > > Newvill**(USA*) and *Dr. Grant Bunker**(USA*). They have presented their > > lecture on Athena and Artimis software.But I want to learn more about to > > FEFFIT software .so how i get more knwoledge about these soaftware by > > analyzing data. i wiil waiting for your answer in soon future on my > mail. > > > > your siencerly > > *Samrath Ninama* > > *Email : samrathn(a)gmail.com* > > SOP,DAVV ,*Indore* [mp] *INDIA* > > -- > > Bruce Ravel ------------------------------------ bravel(a)bnl.gov > > National Institute of Standards and Technology > Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 > Building 535A > Upton NY, 11973 > > My homepage: http://xafs.org/BruceRavel > EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/ > ----------------------------------------- -- Bruce Ravel ------------------------------------ bravel(a)bnl.gov National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973 My homepage: http://xafs.org/BruceRavel EXAFS software: http://cars9.uchicago.edu/ifeffit/Demeter

1 0

More for dealing the LCF
by Hana 09 Sep '11

09 Sep '11

I would be happy to get advices for LCF of EXAFS spectra, at the following context: 1. Constraining the sum of components fractions to one – - when to apply? - Which factors should be considered at this context while working with soil samples? - How would you suggest dealing the penalty when sum of components is different than one in these heterogeneous soil samples (with unknown composition and probably high effect of disorder)? 2. Any reason not to constrain all fractions to be positive? Thanks, Hana

2 1

Request on behalf of V. Petkov
by Anatoly I Frenkel 08 Sep '11

08 Sep '11

Dear members of the mailing list, I am forwarding to you a request from Valeri Petkov, an organizer of a workshop on nanomaterials at the Denver X-ray conference: ***** We need an instructor for a workshop at the X-ray conference in Denver, Colorado at the first week of August, 2012, who can give an intro (45 mins) to EXAFS basics as applied to study nanoparticles and then provide training/demo (another 45 mins) on EXAFS data analysis using some of the freely available software packages. ***** Perhaps, some of you are available to contribute to this effort. In that case, please contact Valeri directly: petkov(a)phy.cmich.edu] Thank you, Anatoly

1 0

Fitting on Athena
by Niken Wijaya 08 Sep '11

08 Sep '11

Hi Everyone, I am facing a lot of problems when I am trying to fit my sample's spectra with my standards one. Initially, I used Athena to do the background subtraction, but the fitting results are just too "funny". The fitting does not really fit the actual spectra. Since I am analyzing Sulphur and many papers has reported how it is prone to self-absorption effect, I thought, probably if I am using a better background subtraction such as MBACK, I would get a better results. So I decided to use it for the normalization and unlike in Athena, the normalized intensity of the spectra does not equal to 1. By saying this, the intensity of my standard models is way higher than the actual samples. Hence, when I use Athena to fit my real spectra, I would not get a good results. I have also tried using the 3rd derivative of my absorption spectra, but the fitting results are even worse. The intensity of the "fit" spectra is way higher than the actual spectra of my samples that I am trying to fit it with. In fact, when I stack the spectra from the standards and the sample together, the 3rd derivative peak of the samples is almost completely flat due to the very high intensity of the standards themselves. What did I do wrong? and what can I do to fix it? I have also attached my samples and standards spectra. Thank you very much for the assistance. Niken

4 6

Re: [Ifeffit] Ifeffit Digest, Vol 103, Issue 7
by Rajesh Kumar 06 Sep '11

06 Sep '11

Dear Matt, Thanks for your mail. I moved with your advice with PGPLOT a couple of weeks back. After that I could install PGPLOT. Then I installed ATHENA, ARTEMIS and there were some error messages when I was trying to run FIT in ARTEMIS. I tried to resolve them, but then I thought of testing the installation of PGPLOT and then I found that the demos were not working. Since at that time I had tried to install different versions of IFEFFIT, ATHENA and DEMETER, my system got cluttered. So I cleaned the system. Removed all the programs. I installed PGPLOT, HORAE though ubuntu afresh. Then I started to run the demos of PGPLOT. with advice from Pawel, I was able to run compile and execute the .f programs. with "I am not able to run the demo programs" meant that at that time I was not able to run the PGPLOT demos. As I mentioned running PGPLOT demos was just a check, my goal is to use IFEFFIT, ATHENA and now I would be moving to that. With regards Rajesh On 6 September 2011 22:30, <ifeffit-request(a)millenia.cars.aps.anl.gov>wrote: > Send Ifeffit mailing list submissions to > ifeffit(a)millenia.cars.aps.anl.gov > > To subscribe or unsubscribe via the World Wide Web, visit > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > or, via email, send a message with subject or body 'help' to > ifeffit-request(a)millenia.cars.aps.anl.gov > > You can reach the person managing the list at > ifeffit-owner(a)millenia.cars.aps.anl.gov > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Ifeffit digest..." > > > Today's Topics: > > 1. Re: Regarding the execution of Demos in PGPLOT (Matt Newville) > 2. Re: Looking for reviewers for data reduction chapter (Wei Li) > 3. Re: Question on GaN Artemis fit (esp. So2 factor) (Matt Newville) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 6 Sep 2011 09:03:55 -0500 > From: Matt Newville <newville(a)cars.uchicago.edu> > To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: Re: [Ifeffit] Regarding the execution of Demos in PGPLOT > Message-ID: > <CA+7ESbqeQ87-wy8OvdDn_unfWXQtzg6DUVR-Os-TJf+v_rEmkg(a)mail.gmail.com > > > Content-Type: text/plain; charset=ISO-8859-1 > > Rajesh, > > > On Tue, Sep 6, 2011 at 7:52 AM, Rajesh Kumar <rajesh.sdc(a)gmail.com> wrote: > > I recently installed > > 1. PGPLOT 5 (ver: 5.2.2-15) through Synaptic Package Manager from ubuntu > - > > MOTU-Developers (Mathematics, Multiverse) > > 2. IFEFFIT from Carlo Segre < segre(a)debian.org>, (version > > 2:1.2.11d-6~lucid0 ) and > > 3. Horae-07-1 through Synaptic Package Manager from ubuntu - developers > > (Science, Multiverse) > > I am not able to run the demo programs. So I started running demo > programs > > for PGPLOT first. > > My examples are in directory: > > /usr/share/doc/pgplot5/examples/pgdemo2.f.gz > > When I compile the program "depgplot10.f" and executed the file, the > > interaction on the console is attached in the file attached herewith. > > I need help in this regard and I am very very new to "xafs" as well as > > ubuntu. > > As far as I can tell from the message you attached, you ran a PGPLOT > demo program that requires a cursor for user input, selected a device > that does not support user input, and got a message saying so. That > seems reasonable to me... you might try selecting the /XW device. > > But, is running the PGPLOT demos your goal? What does that have to do > with Ifeffit? If running Ifeffit is the goal, what happens when you > try to run the programs ifeffit or athena? What does "I am not able > to run the demo programs" mean? > > --Matt > > > ------------------------------ > > Message: 2 > Date: Tue, 6 Sep 2011 10:57:43 -0400 > From: Wei Li <weili(a)udel.edu> > To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: Re: [Ifeffit] Looking for reviewers for data reduction > chapter > Message-ID: > <CAG_WZxfBDkd4Vbr7GTSEV0n=-CT=FZ=9OrOMVoCt4OoM83AXxA(a)mail.gmail.com > > > Content-Type: text/plain; charset="iso-8859-1" > > Hi, Scott, > > I am also glad to read the chapter. > > Wei > > On Sat, Sep 3, 2011 at 7:13 PM, Lachlan MacLean < > Lachlan.MacLean(a)lightsource.ca> wrote: > > > Hi Scott > > > > I'm in! > > > > Cheers > > Lachlan > > ________________________________________ > > From: ifeffit-bounces(a)millenia.cars.aps.anl.gov [ > > ifeffit-bounces(a)millenia.cars.aps.anl.gov] On Behalf Of Scott Calvin [ > > scalvin(a)sarahlawrence.edu] > > Sent: September 3, 2011 3:16 PM > > To: XAFS Analysis using Ifeffit > > Subject: [Ifeffit] Looking for reviewers for data reduction chapter > > > > Hi all, > > > > Once again, I have a draft of a chapter of my textbook ready for review. > > This chapter is on data reduction, including normalization, background > > subtraction, and Fourier transforms. This will be Chapter 4 in the book, > so > > it should be suitable for near-beginners as well as those with more > > experience. This is also a chapter where I had to make a lot of decisions > on > > nomenclature and presentation, so experts might be interested as well, > > particularly if you have strong opinions on that kind of thing! It is a > bit > > more than 40 pages long, which makes it the longest so far. > > > > If you are interested in reviewing the chapter and can get feedback to me > > by 29 September, please contact me directly at SCalvin(a)slc.edu . As > > always, repeat reviewers are welcome! > > > > --Scott Calvin > > Sarah Lawrence College > > _______________________________________________ > > Ifeffit mailing list > > Ifeffit(a)millenia.cars.aps.anl.gov > > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > > > > _______________________________________________ > > Ifeffit mailing list > > Ifeffit(a)millenia.cars.aps.anl.gov > > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > > > > > > -- > Wei Li > > Postdoc researcher > Environmental Soil Chemistry Group > Delaware Environmental Institute > University of Delaware, Newark,19713 > Tel:631-949-0663 > http://ag.udel.edu/soilchem/li.html <http://ag.udel.edu/soilchem/> >

2 1

Question on GaN Artemis fit (esp. So2 factor)
by Alejandro X Levander 06 Sep '11

06 Sep '11

Dear ifeffit community; I am working on modeling the local structure of amorphous GaN(1-x)As(x) alloys. After helpful learning experiences at the SSRL XAS Summer School and reading Scott Calvin's doped material help page, I was able to model all of the data for the As K edge I had collected. However, I am now having issues modeling the Ga K edge spectra despite using similar methods. I expect the Ga to be tetrahedrally coordinated and bonded to a mixture of As and N based on the previously determined overall composition. To determine the SO2 parameters for the Ga K edge I am using data collected in fluorescence mode of a thin film (690 nm) of GaN on a sapphire (Al2O3 - 500um) substrate as a reference sample. I have fixed the first and second shell amplitudes in order to determine SO2. The SO2 parameter for the nitrogen shell appears too low to be physically correct (~0.5). When I use these values for SO2 to try and model my amorphous films, I get highly unexpected coordination values much larger than four when summed for As and N bonding since the model is compensating for the low SO2. I am concerned there may be an issue with the data processing in Athena (e.g. self-absorption or deglitching) or multiple-scattering, but cannot pin down the problem. I have attached the GaN (sample code sn281) Athena and Artemis files and an example of trying to fit the Ga K edge of amorphous GaN(0.55)As(0.45) material in Artemis (sample code sn404). The amorphous thin film was 220 nm thick on a 500um pyrex glass substrate measured in fluorescence mode. As a side note, I have also been having trouble with using ATOMS for the wurtzite crystal structure. Despite trying multiple appropriate .cif files from ICSD and making sure to use 1/3 instead of 0.33334 when I run ATOMS, there appear to be rounding errors that turn one coordination into three. Thus I have been manually changing the feff input. Any help is greatly appreciated, Alejandro

2 1