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

book chapter
by Hashem Stietiya 16 Jan '09

16 Jan '09

Dr. Kelly, I would be thrilled if you could send me a copy. Thank you, Hashem Stietiya Louisiana State University -----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, January 15, 2009 12:00 PM To: ifeffit(a)millenia.cars.aps.anl.gov Subject: Ifeffit Digest, Vol 71, Issue 16 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: distinguishing between actual shells and artifacts (Kelly, Shelly) ---------------------------------------------------------------------- Message: 1 Date: Wed, 14 Jan 2009 13:58:21 -0700 From: "Kelly, Shelly" <Shelly.Kelly(a)uop.com> Subject: Re: [Ifeffit] distinguishing between actual shells and artifacts To: "XAFS Analysis using Ifeffit" <ifeffit(a)millenia.cars.aps.anl.gov> Message-ID: <5A8CCCCD35FC0946BE602D2F43C0218A7DF9FF(a)AZ18EV808.global.ds.honeywell.com> Content-Type: text/plain; charset="iso-8859-1" Hi Hashem, I show one method for doing this in my book chapter Figure 14-23 on page 431. (I feel a bit like a broken record). I will send you a copy if you want. Shelly > -----Original Message----- > From: ifeffit-bounces(a)millenia.cars.aps.anl.gov [mailto:ifeffit- > bounces(a)millenia.cars.aps.anl.gov] On Behalf Of Voegelin Andreas > Sent: Wednesday, January 14, 2009 9:57 AM > To: XAFS Analysis using Ifeffit > Subject: Re: [Ifeffit] distinguishing between actual shells and artifacts > > Hi Hashem > > You can copy-paste the respective EXAFS data in Athena and compare the > backtransforms over the first shell, the first+second shell, the second > shell. > > By comparison of the backtransforms with each other and with the measured > EXAFS, you can see where the second-shell contribution has its origin in > k-space (note that the backtransform is not corrected for the window > function). > > For instance, if the second-shell signal adds to the spectrum in the low-k > range (where noise should not be a problem), it is likely real and might > result, e.g., from multiple scattering among first-shell O atoms. If the > second-shell signal in the backtransform mainly contributes in the high-k > range (where noise or glitches may be a problem), you may be able to see > whether it falls together with obvious artefacts (such as glitches), or > whether the backtransform matches spectral features that you consider to > be real. > > Andreas > > ----------------------------------------------- > Andreas Voegelin, PhD > Soil Chemistry Group > Inst. of Biogeochemistry and Pollutant Dynamics > Dept. of Environmental Sciences > ETH Zurich > Universit?tstrasse 16, CHN F24 > CH-8092 Z?rich, Switzerland > Phone: +41 44 633 61 47 > Fax: +41 44 633 11 18 > E-Mail: voegelin(a)env.ethz.ch > www: http://www.ibp.ethz.ch/people/andreavo > > > > > -----Original Message----- > > From: ifeffit-bounces(a)millenia.cars.aps.anl.gov > > [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On Behalf > > Of mstiet2(a)lsu.edu > > Sent: Mittwoch, 14. Januar 2009 14:12 > > To: ifeffit(a)millenia.cars.aps.anl.gov > > Subject: [Ifeffit] distinguishing between actual shells and artifacts > > > > Dear all, > > > > I am currently fitting first and second shells with Zn-O and > > Zn-Zn paths,respectively. I get second shell features that > > could be fit quite well, but I am not certain if they are > > actually second shell features or possibly artifacts. For > > some samples I get second shell features that I know should > > not be present. What criteria would you use to distinguish > > between artifacts and actual shells? > > > > Your assistance is appreciated. > > > > Hashem Stietiya > > > > Louisiana State University > > > > > > > > _______________________________________________ > 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 End of Ifeffit Digest, Vol 71, Issue 16 ***************************************

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difference between Zn-Zn/Fe and Zn-Fe paths
by Hashem Stietiya 16 Jan '09

16 Jan '09

Dear All, Is there a difference between fitting a second shell with two separate paths (Zn-Zn path and a Zn-Fe path) each with its own parameters and fitting that second shell with a combination of two paths (Zn-Zn/Fe)? When would I choose to do that latter, and how? I hope I made myself clear! Thanks, Hashem Stietiya Louisiana State University

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SCF and FMS radius
by Eugenio Otal 15 Jan '09

15 Jan '09

Hello, I am simulating the XANES spectra of a erbium atom in an interstitial site of ZnO. I needed a SCF radius of 9.75 (316 atoms) and FMS radius of 11.90 (599 atoms) to obtain no change in the simulated spectra (differences of 0.01% or less) Now I am trying to simulate Er(OH)3 and it is using SCF 10.90 (622 atoms) and I still haven found convergence, I will need more even larger radius for FMS. Does the XAS phenomena have this distances? Has this distances physical meaning? Thanks, euG 8<- - - - - - 8<- - - - - - 8<- - - - - - 8<- - - - - - Lic. Eugenio H. Otal E-mail: eotal(a)citefa.gov.ar eugenioh(a)gmail.com 8<- - - - - - 8<- - - - - - 8<- - - - - - 8<- - - - - -

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distinguishing between actual shells and artifacts
by mstiet2＠lsu.edu 14 Jan '09

14 Jan '09

Dear all, I am currently fitting first and second shells with Zn-O and Zn-Zn paths,respectively. I get second shell features that could be fit quite well, but I am not certain if they are actually second shell features or possibly artifacts. For some samples I get second shell features that I know should not be present. What criteria would you use to distinguish between artifacts and actual shells? Your assistance is appreciated. Hashem Stietiya Louisiana State University

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How to keep enot,delr, and ss within acceptable limits
by Hashem Stietiya 14 Jan '09

14 Jan '09

Dear All, I am currently using ARTEMIS to fit Zn-O, Zn-Zn paths to first and second shells, respectively. Many times I would get unacceptable values for enot, ss, and delr. My question is: is there a way to tell ARTEMIS that I want these parameters to be within acceptable limits? For example, you cannot have negative ss, so how can I avoid any fit result that produces negative values for ss? Or high extremely high values for enot and delr? I appreciate your assistance and guidance. Regards, Hashem Stietiya School of plant, Environmental and Soil Sciences Louisiana State University

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Trouble with fitting with Arthemis
by Kleper Oliveira Rocha 13 Jan '09

13 Jan '09

Hi all, Please, help me. When I try to do any fit in Arthemis, setting all parameters unless one, been this one any of the parameters, the fit gives for the answer -1.0000 +/- 0.000000 like example down. What is happening? ============================================================ Independent points = 8.239257812 Number of variables = 1.000000000 Chi-square = 0.120000000E+37 Reduced Chi-square = 0.165762849E+36 R-factor = NaN Measurement uncertainty (k) = 0.000437667 Measurement uncertainty (R) = 0.000724906 Number of data sets = 1.000000000 Guess parameters +/- uncertainties (initial guess): * amp = -1.0000000 +/- 0.0000000 (1.0000)* Set parameters: enot = 0 delr = 0 ss = 0.003 c3 = 0.0001 c4 = 0.00001 -- Kleper de Oliveira Rocha Chemical Engenieer Doctorated Tels. 55 016 3351-8694

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Re: [Ifeffit] SCF and FMS radius
by joshua jason kas 13 Jan '09

13 Jan '09

Hi Eugenio, I would call all of the spectra that you sent converged. It is true that they are not the same to all digits of output, but you really don't need things to be that accurate. Theoretical and experimental errors are much larger, especially in the near edge. When converging w.r.t. the SCF and FMS radius, you really only need to be sure that changes in the spectrum due to finite cluster size are small compared to the differences between theory and experiment. You can probably get by with a much smaller cluster even. Cheers, Josh Kas On Mon, 12 Jan 2009, 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. SCF and FMS radius (Bruce Ravel, Feng Wang & Josh Kas) > (Eugenio Otal) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 12 Jan 2009 23:40:07 -0200 > From: "Eugenio Otal" <eugenioh(a)gmail.com> > Subject: [Ifeffit] SCF and FMS radius (Bruce Ravel, Feng Wang & Josh > Kas) > To: ifeffit(a)millenia.cars.aps.anl.gov > Message-ID: > <da22ad30901121740x764c0babjf20f055285a4d9b2(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hi Bruce, Feng and Josh, > I am simulating erbium hydroxide from its crystal structure information, > what does really mean well ordered? > Of course I can?t answer you that, I hope someday would know the answer, and > for the dummies question... I see the changes only close to the edge. > I?ll read the paper deeply , and what I see in the abstract, the SCF and FMS > should converge faster. > I attach 3 packages with 3 results and its .inp files, I hope you can help > me. > Thanks in advance, euG >

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looking for Zn(OH)2 EXAFS spectrum
by Samuel Legros 13 Jan '09

13 Jan '09

Hi everybody, I am loking for the Zn(OH)2 EXAFS spectrum. If someone have it, i would be very grateful if he (or she) would like to send it to me. Thank you in advance -- Samuel LEGROS Doctorant CIRAD basé au CEREGE Directeur : Emmanuel DOELSCH Europole de l'arbois BP 80 13545 Aix-en -provence FRANCE Tel : 04 42 97 17 76 Fax : 04 42 97 15 59

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SCF and FMS radius (Bruce Ravel, Feng Wang & Josh Kas)
by Eugenio Otal 12 Jan '09

12 Jan '09

Hi Bruce, Feng and Josh, I am simulating erbium hydroxide from its crystal structure information, what does really mean well ordered? Of course I can´t answer you that, I hope someday would know the answer, and for the dummies question... I see the changes only close to the edge. I´ll read the paper deeply , and what I see in the abstract, the SCF and FMS should converge faster. I attach 3 packages with 3 results and its .inp files, I hope you can help me. Thanks in advance, euG

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Re: [Ifeffit] Ifeffit Digest, Vol 71, Issue 8
by joshua jason kas 12 Jan '09

12 Jan '09

Hi Eugenio, I am not familiar whith the system, but it seems a bit strange to me. What edge are you running? Can you send some of your calculations and a feff input file? I've seen cases where the FMS is still not converged at 1000 atoms, but the SCF radius usually converges much faster. Cheers, Josh Kas > > Hello, > I am simulating the XANES spectra of a erbium atom in an interstitial site > of ZnO. I needed a SCF radius of 9.75 (316 atoms) and FMS radius of 11.90 > (599 atoms) to obtain no change in the simulated spectra (differences of > 0.01% or less) > Now I am trying to simulate Er(OH)3 and it is using SCF 10.90 (622 atoms) > and I still haven found convergence, I will need more even larger radius for > FMS. > Does the XAS phenomena have this distances? Has this distances physical > meaning? > Thanks, euG > > > > > > > > > 8<- - - - - - 8<- - - - - - 8<- - - - - - 8<- - - - - - > > Lic. Eugenio H. Otal > E-mail: eotal(a)citefa.gov.ar > eugenioh(a)gmail.com > > 8<- - - - - - 8<- - - - - - 8<- - - - - - 8<- - - - - - >

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