July 2009 - Ifeffit - millenia.cars.aps.anl.gov

new release of my software
by Bruce Ravel 05 Jul '09

05 Jul '09

Hi everyone, Windows users should soon see that an update is available. This is a relatively small thing -- it contains a new build of Athena with fixes for several recently repoted bugs. As always, it should get installed sometime soon when you fire up one of the Ifeffit programs. For those who build from source, I have also uploaded a new tarball to my web site (already there) and to SourceForge (available soon). Along with the bug fixes to Athena, this new tarball (horae-070) is my attempt to address the serious problems many of you have had in recent months trying to get my codes installed from source. The current tarball contains all of horae as well as all of my libperlxray modules. It also includes all the files required to install the Athena User's Guide (which is why the new tarball is so much larger than previous ones). I have writen a general build script and attempted to explain the installation procedures clearly is files fouond at the top of tarball. Let me know how it goes. For those of you who use the SVN server for the source code, that remains a useful alternative to using the tarball. There is no code in the tarball that is not in the SVN repository. Regards, B -- 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/

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Re: [Ifeffit] Ifeffit Digest, Vol 77, Issue 8
by abhijeet gaur 05 Jul '09

05 Jul '09

Hello Sir, I am fitting Cu2O at room temperature. I got the point. So, the negative value of SS parameter is due to the low value of SO2 guessed by artemis. I have done the fitting again by fixing the value of SO2 to 0.7. Now I am gettig positive value of SS parameter which is around 0.007. Please tell me from where I can get the standard value of SO2 calculated theoretically in the literature. with regards Abhijeet Gaur Dear Abhijit, > > > > The parameters So2 and SS are highly correlated. The negative value of SS > does not make any physical significance. It may be due that Artemis is > conveging for lower value of So2. In your case (So2=0.552 or 0.61) it is > very low. Generelly, it should be in the range of 0.7 to 1. It will be > better if you fix So2 for the standard value calulated theoretically in the > literature or you can try to get approximated value of SS for So2 around 0.8 > to 0.9. > > > > regards > > > > Umesh Palikundwar > > Department of Physics > > RTM Nagpur University, > > Nagpur-440033 > > _________________________________________________________________ > Missed any of the IPL matches ? Catch a recap of all the action on MSN > Videos > http://msnvideos.in/iplt20/msnvideoplayer.aspx >

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Re : Cu2O fitting
by abhijeet gaur 04 Jul '09

04 Jul '09

Hi all, Thanks for the response. I am sorry as I should attach the figure in a viewable format. Anyways now I am attaching a the artemis project file in which I had used a set positive value for the SS parameter of first path. I am not able to understand the reason for negative SS value. Thanks again Abhijeet Gaur

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Re: [Ifeffit] Fitting Cu2O
by umesh palikundwar 04 Jul '09

04 Jul '09

> Hi all, > I am fitting Cu2O data. But when I fit the first shell using the > first path, I got the guess value for SS parameter negative which is around > -0.0028 and also the guessed value for SO2 parameter comes out to be around > 0.52. Are these values logically correct as I am getting a nice fit. > Also when I use the same SS parameter but with positive sign for the > first shell i.e., 0.0028, the guessed value for SO2 parameter comes out to > be 0.61. > When I fit the higher shells by using the same SO2 and Enot value for > other paths, the value of SS parameter for these paths is coming very high , > i.e., 0.016 - 0.021. But the fit seems to be quiet good. Are these higher > values of SS parameter correct. The resulting figure is attached. > > with thanks > > Abhijeet Gaur > > School of Studies in Physics > > Vikram University, Ujjain, INDIA. Dear Abhijit, The parameters So2 and SS are highly correlated. The negative value of SS does not make any physical significance. It may be due that Artemis is conveging for lower value of So2. In your case (So2=0.552 or 0.61) it is very low. Generelly, it should be in the range of 0.7 to 1. It will be better if you fix So2 for the standard value calulated theoretically in the literature or you can try to get approximated value of SS for So2 around 0.8 to 0.9. regards Umesh Palikundwar Department of Physics RTM Nagpur University, Nagpur-440033 _________________________________________________________________ Missed any of the IPL matches ? Catch a recap of all the action on MSN Videos http://msnvideos.in/iplt20/msnvideoplayer.aspx

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Re: [Ifeffit] orbital configuration (FEFF8)
by joshua jason kas 04 Jul '09

04 Jul '09

Hi Iraida, I believe there are a few issues here that could be addressed/explained. First, the electronic configuration given at the end of the potentials is only the configuration of the valence electrons. For example the absorbing oxygen should be interpreted as 0 0 1.953 ~2s2 0 1 5.159 ~2p5 (The ~1 extra valence electron for the absorbing atom is due to the attractive core hole) 0 2 0.040 0 3 0.000 while for Cd 1 0 0.723 ~5s1 1 1 0.711 ~5p1 1 2 10.149 ~4d10 1 3 0.000 Here, the differences from the atomic configuration of 4d10 5s2 are due to the fact that this is a self-consistent solid state configuration, i.e. the valence electrons were allowed to relax and were effected by the solid state potential. That being said, there are ways to change the initial configuration for the elements, but you would have to change the source code and recompile. I don't think this is what you want to do though. As for improving your results, there may be a variety of things that you can do. Off hand your input file looks pretty good. One thing you might try is using the card UNFREEZEF which allows the d electrons from the Cd to tranfer to f states which can sometimes be important when the d band is full. I hope that my answer helps some, at least in interpreting FEFFs output. Josh Kas > Hi everyone,I > would like to calculate K-edge of oxygen XANES spectrum for CdO film. I > attached my feff.inp file to this e-mail. When I check log1.dat file I > observe next information: > "... > Electronic configuration > iph il N_el > 0 0 1.953 //comment: 0-centr.atom (O) > 0 1 5.159 > 0 2 0.040 > 0 3 0.000 > 1 0 0.723 //comment: 1-Cd > 1 1 0.711 > 1 2 10.149 > 1 3 0.000 > 2 0 1.921 //comment: 2-O > 2 1 4.443 > 2 2 0.052 > 2 3 0.000 > mu_new= -5.168 > Charge transfer: iph charge(iph) > 0 -0.152 > 1 0.417 > 2 -0.417 > Done with module 1: potentials." > > As > is well known, orbital configuration for Cd and O is: 4d10 5s2 and 1s2 > 2s2 2p4, respectively. I think that obtained results for Cd differ much > according to presented orbital configuration (s,p). So, my question is: > do there exist some possibilities to change something in my feff.inp > file to improve the results? > > Best regards, > Iraida. > > > >

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Fitting Cu2O
by abhijeet gaur 03 Jul '09

03 Jul '09

Hi all, I am fitting Cu2O data. But when I fit the first shell using the first path, I got the guess value for SS parameter negative which is around -0.0028 and also the guessed value for SO2 parameter comes out to be around 0.52. Are these values logically correct as I am getting a nice fit. Also when I use the same SS parameter but with positive sign for the first shell i.e., 0.0028, the guessed value for SO2 parameter comes out to be 0.61. When I fit the higher shells by using the same SO2 and Enot value for other paths, the value of SS parameter for these paths is coming very high , i.e., 0.016 - 0.021. But the fit seems to be quiet good. Are these higher values of SS parameter correct. The resulting figure is attached. with thanks Abhijeet Gaur School of Studies in Physics Vikram University, Ujjain, INDIA.

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Fitting Cu2O
by abhijeet gaur 03 Jul '09

03 Jul '09

Hi all, I am fitting Cu2O data. But when I fit the first shell using the first path, I got the guess value for SS parameter negative which is around -0.0028 and also the guessed value for SO2 parameter comes out to be around 0.52. Are these values logically correct as I am getting a nice fit. Also when I use the same SS parameter but with positive sign for the first shell i.e., 0.0028, the guessed value for SO2 parameter comes out to be 0.61. When I fit the higher shells by using the same SO2 and Enot value for other paths, the value of SS parameter for these paths is coming very high , i.e., 0.016 - 0.021. But the fit seems to be quiet good. Are these higher values of SS parameter correct. The resulting figure is attached. with thanks Abhijeet Gaur School of Studies in Physics Vikram University, Ujjain, INDIA.

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orbital configuration (FEFF8)
by Dream Dream 02 Jul '09

02 Jul '09

Hi everyone,I would like to calculate K-edge of oxygen XANES spectrum for CdO film. I attached my feff.inp file to this e-mail. When I check log1.dat file I observe next information: "... Electronic configuration iph il N_el 0 0 1.953 //comment: 0-centr.atom (O) 0 1 5.159 0 2 0.040 0 3 0.000 1 0 0.723 //comment: 1-Cd 1 1 0.711 1 2 10.149 1 3 0.000 2 0 1.921 //comment: 2-O 2 1 4.443 2 2 0.052 2 3 0.000 mu_new= -5.168 Charge transfer: iph charge(iph) 0 -0.152 1 0.417 2 -0.417 Done with module 1: potentials." As is well known, orbital configuration for Cd and O is: 4d10 5s2 and 1s2 2s2 2p4, respectively. I think that obtained results for Cd differ much according to presented orbital configuration (s,p). So, my question is: do there exist some possibilities to change something in my feff.inp file to improve the results? Best regards, Iraida.

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problem with Athena's E0 !
by Arezki, Bahia 01 Jul '09

01 Jul '09

Hi all, I am using Athena (version: 08.058) to study the changes in the XANES profiles as a function of temperature of an organometallic compound containing Fe. I have a problem with the E0 value suggested by Athena : I noticed that it is not taking the same maximum in the first derivative. I am sending 2 examples of xanes taken at RT ( E0 guessed is 1722.8 eV ) and 10 K (1727.3 eV !), can any one help me please to solve this problem ? should I force athena to take the first maximum at 1722 eV ? I tough that my spectra have been properly calibrated: I first calibrated the iron foil -reference channel (E0=1712 eV) of a sample xanes and then I aligned the rest of the reference channels to that one. I though this was enough to calibrate my data. can you please tell me if my data processing is correct? I need to be sure about the E0 value in order to know the correct shift of the different xanes features as a function of temperature. Also, with a wrong E0 the normalization is not correct...did I miss an important step? I am having hard time with these basic questions...before using linear combination analysis and peak fitting analysis. Of course I have already looked in the IFFEFIT archive, but I did not find such problem. I only found a question about a wrong E0 because taken before the edge which is not my case. Thanks so much for your time, Bahia

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