Hello, my name is Andreas Schacht and I am working with germanium and germanium oxides in my diploma thesis. Therefore I was trying to simulate the XANES spectra of both with feff. The results for germanium seem to be very good in comparison to the experimental data but the simulated spectra of GeO2 in the alpha-quartz structure is far away from all the experimental spectra I have seen. So I was wondering if someone has some experience with calculating the XANES spectra of germanium oxides. Thanks for any help. Best regards Andreas -- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/
Hi Andreas, I don't really qualify as "someone who has some experience with calculating XANES spectra", but I remeber reading something about GeO2 input files when studying Artemis' manual. If you take a look at the manual you'll see that there might be a problem with GeO2 and a shift vector may have to be added in the creation of the FEFF input file. By the way, which FEFF input file are you using? The cassiterite-like from the atoms/webatoms database? Or have you created your own input file? Anyways, adding the shift vector may be a solution. Hope this helps, Leandro
Hi Leonardo, thanks for your quick reply. I have read about the problem with the shift vector and tried therefore several configurations, but none of them work out. The data for the input file was taken from the "American Mineralogist Crystal Structure Database": GeO2 Smith G S, Isaacs P B Acta Crystallographica 17 (1964) 842-846 The crystal structure of quartz-like GeO2 Note: polymorph of argutite 4.987 4.987 5.652 90 90 120 *P3_221 0 0 .6666666666666 atom x y z B(1,1) B(2,2) B(3,3) B(1,2) B(1,3) B(2,3) Ge .4513 0 0 .0076 .0067 .0042 .0034 0 0 O .3969 .3021 .0909 .0192 .0142 .0083 .0118 -.004 -.003 The input file for FEFF was than created with webatoms and I allready visualized the calculated coordinates and the results look like a quartz-structure so I am not quite sure if this is the problem. The FEFF-calculation itself was done with more than 100 atoms and as far I can tell the calculated DOS doesn't look so bad compared to other DFT-calculations of alpha-quartz GeO2. So if someone has an idea what to try next... Thanks again. Regards Andreas
participants (3)
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Andreas Schacht -
Andreas Schacht -
Leandro Araujo