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

Two absorbing atom sites
by Yun Luo 05 Nov '09

05 Nov '09

Dear IFEFFIT List, I learned that IFEEFIT can model a single absorber in two different environment. Could anyone direct me to similar studies that have been done or related tutorials? Below are some thoughts and questions: For example, there is 2 wt% A in both M1 and M2 structural sites in crystal X as dopant. I first create 2 FEFF models in Artemis, one has absorbing atom A only in M1 site and the other one has A only in M2 site. In the fitting process, is it correct that I choose paths from both FEFF models and using different Eo and So^2 for M1 and M2 sites? And to model the site occupancy of A in each site, I can create a fraction parameter "a" (which means there are a*2 wt% A in M1 site and (1-a)*2 wt% A in M2 site). Is it correct to apply this fraction parameter only to So^2 to model the site occupancy of A in M1 and M2 site? I am worried this approach will use too many variables. Any suggestions on the constraints/restraints that I can use? Finally, is there anything else that I missed which needs to be considered to do the modeling for this case of two different absorbing atom sites? Any suggestion will be greatly appreciated! Thank you all in advance! Best regards! Yun

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Reference materials for Ca & Cd for XANES
by Varadarajan Sridharan 03 Nov '09

03 Nov '09

Dear Sir, I am planning to carryout the XANES measurements on Cd(1-x)Ca(x)O solid solution to determine the electronic state. Can you suggest me the reference materials for Ca(2+) K-edge and Cd(2+) L-edge for XANES studies. Thanking you in advance V. Sridharan --------- CMPD, IGCAR Kalpakkam, INdia

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Problem with EXAFS simulations: endless loop
by Cammelli Sebastiano 03 Nov '09

03 Nov '09

Dear feff user I try to simulate the EXAFS spectrum of a matrix composed of Fe and Cr (2 atoms on 35) at the Cr K edge. Well, I do not why, but feff (both 8.2 and 8.4) generates an endless loop. Here below I report the feff.inp used. I try even with different value of the SCF card (7.0 1 30 0.05 10) (4.0 1 30 0.05 10) (2.0 1 30 0.2 1) (3.0 1 30 0.2 1) but nothing changes. In order to solve the problem I should not use the SCF card, but this solution brings to a worse evaluation of the E0 and generally, from my little experience, I prefer to use it. The atoms coordinates were calculated by MD. Thank you very much for any help or suggestion. Best Sebastiano TITLE Cr in Fe matrix CONTROL 1 1 1 1 1 1 PRINT 0 0 0 0 0 0 RMULTIPLIER 1.003 LDOS -30 20 0.2 EDGE K S02 1.0 SCF 4.0 1 30 0.2 1 DEBYE 60 470 0 EXCHANGE 0 0 0 0 CORRECTIONS 0 2.5 EXAFS RPATH 10.0 POTENTIALS 0 24 Cr -1 -1 1 26 Fe -1 -1 2 24 Cr -1 -1 ATOMS -2.83900 -2.83700 -2.83600 1 Fe -1.41600 -1.41600 -1.41500 1 Fe 0.00000 0.00000 0.00000 0 Cr 2.84600 2.84500 2.84300 1 Fe 0.01340 2.84000 2.83900 1 Fe 2.84000 0.01200 2.83900 1 Fe 0.01200 0.01200 2.83200 1 Fe 2.84000 2.83900 0.01050 1 Fe 0.01200 2.83200 0.01000 1 Fe 2.83200 0.01000 0.01000 1 Fe 1.43000 1.42900 1.42800 2 Cr -2.83300 2.84500 2.84300 1 Fe -2.83900 0.01200 2.83900 1 Fe -2.83900 2.83900 0.01050 1 Fe -2.84700 0.01000 0.01000 1 Fe -1.40200 1.41900 1.41800 1 Fe 2.84300 -2.83400 2.84300 1 Fe 0.01050 -2.83900 2.83900 1 Fe 2.83700 -2.84100 0.01050 1 Fe 0.00900 -2.84700 0.01000 1 Fe 1.41800 -1.40300 1.41800 1 Fe -2.83600 -2.83400 2.84300 1 Fe -2.84200 -2.84100 0.01050 1 Fe -1.41000 -1.40900 1.41800 1 Fe 2.84300 2.84200 -2.83600 1 Fe 0.01050 2.83700 -2.84100 1 Fe 2.83700 0.00910 -2.84100 1 Fe 0.00900 0.00870 -2.84700 1 Fe 1.41800 1.41800 -1.40600 1 Fe -2.83600 2.84200 -2.83600 1 Fe -2.84200 0.00910 -2.84100 1 Fe -1.41000 1.41700 -1.41000 1 Fe 2.84100 -2.83700 -2.83600 1 Fe 0.00770 -2.84200 -2.84100 1 Fe 1.41700 -1.41100 -1.41000 1 Fe END

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Re: [Ifeffit] Installing Athena on a Mac
by Bruce Ravel 02 Nov '09

02 Nov '09

Minna, As I point out regularly on the mailing list, I am not a Mac user and do not maintain the mac packages. You really need to inquire on the mailing list for support in that area -- that way you will actually find the people who *can* help you. Here are some recent threads on the mailing list regarding Mac installation issues: http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2009-September/009018.ht… http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2009-October/009077.html Perhaps your answer is there. If not, please feel free to make a new request for help on the list. Here is more information about the resources available to you: http://cars9.uchicago.edu/ifeffit/BruceRavel/FormLetters/HelpRequest As I explain there, the mailing list should always be your first stop when you have a question about the software. B PS: If any of the Mac users out there would like to update the Macintosh Issues section of http://cars9.uchicago.edu/ifeffit/FAQ/Installing_Ifeffit that would be really splendid. On Monday 02 November 2009 04:09:22 pm you wrote: > Hello Bruce, > > I'm trying to run Athena on a Mac, OS X Version 10.6.1. Following the > instructions at cars9.uchicago.edu/~ravel/software/downloads.html#mac for a > Macintosh OSX download, I went to SourceForge to download Ifeffit. The > latest version does not appear to be available for Mac download, so I > grabbed > Ifeffit-1.2.10.1-Mac10.4_Intel_horae66.dmg<http://sourceforge.net/projects/ >ifeffit/files/ifeffit/1.2.10/Ifeffit-1.2.10.1-Mac10.4_Intel_horae66.dmg/down >load> , because I'm on an Intel Mac, but the installation failed. I then > grabbed > Ifeffit-1.2.10-Mac10.4_PPC_horae066_pkg.dmg<http://sourceforge.net/projects >/ifeffit/files/ifeffit/1.2.10/Ifeffit-1.2.10-Mac10.4_PPC_horae066_pkg.dmg/do >wnload> and the installation appeared to work, but when I went to run > Athena, X11 opened but nothing else happened. I'm not really sure what the > problem is - can you at least give me a suggestion on where to start? > > Thanks for your help! > > Minna R. Krejci > PhD Candidate - Joester Group > Materials Science and Engineering > Northwestern University > > Cook Hall 3021 > Office: 847 491 3584 > Mobile: 330 603 8608 > minna(a)u.northwestern.edu -- 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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