Re: [Ifeffit] running ifeffit-1.2.11 under 64-bit Windows 7
Dear Sameh, I use also 64 bit Win7 and I do not observe any strange behaviour. All results I got are reasonable, and fitting with different models/starting parameters gives me the same final results (for the same sample, of course). More, I can compare results under Win Xp (old computer) with results under Win7, and I see very good agreement. I run Ifeffit package directly under Win7, I didn't need to run in Win XP mode. U use also Jfeff which runs OK maybe you can tell something more about this strange manner and about your sample/results best regards kicaj W dniu 12-03-07 11:11, sameh pisze: Hi, I have a new computer with 64-bit windows7. I have noticed that Artemis is running in a strange manner, it never produces the same results when the same data is fitted twice. I have uninstalled and then reinstalled the whole (ifeffit-1.2.11) package with the compatibility wizard which suggested to run the package in compatible mode to windows XP. After doing so, any of the programs is not running at all. My old laptop was 32-bit which runs 32-bit windows 7 and the ifeffit-1.2.11 package was running normally with this computer. Thank you very much and best regards Sameh Ibrahim Ahmed ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Re: [Ifeffit] Crystallographic data for V(CO)6
Ismael, You do really not need exact parameters which can is helpful in EXAFS. Can you find any references on the V-C bond length? Since CO is linear, the V-O and V-C-O scattering should be possible to roughly establish. I think a number of general inorganic textbooks might have information such as this on metal carbonyl bonding. If the lattice parameters are not too different, start with simple octahedral geometry and the quick first shell fit using V-C bond length. buena salud, Chris Patridge On Wed, Mar 7, 2012 at 1:39 PM, Ismael Graff gr...@fisica.ufpr.br wrote: Dear XAS fellows: I have to fit EXAFS data of a nanoparticle colloidal suspension. TEM and NMR data indicate that I have nanoparticles of V(CO)_6 (vanadium hexacarbonyl). The system is orthorhombic, space group Pnma (Nr. 62), and I know the nominal values for the lattice parameters. However, I need the different atomic positions/coordinates to enter in ATOMS. Usually I get such information from a CIF (Crystallographic Information File) card. But in this case, I didn´t find it in the open data banks. Is anyone out there that could help me? Cheers, Ismael. PS: A similar structure/material would also help (like Mo(CO)_6)! -- *Ismael Leandro Graff * * * * Universidade Federal do Paraná * * Departamento de Física, CP 19044 * * 81531-990, Curitiba, Brazil. * * Tel (office): +55 41 3361 3278 * * Tel (Lab): +55 41 3361 3427 * * Fax: +55 41 3361 3418* * http://fisica.ufpr.br/graff * ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit -- Christopher J. Patridge PhD. Contact: (315)-529-0501 ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
[Ifeffit] appropriatness of feff model when central atom is not embedded (or only 1 layer embedded)
Hello All, can someone please help with this: (1) feff requires that the adsorbing atom be embedded (that is, surrounded by) other atoms in order to calculate potentials correctly, but how deeply does the atom need to be embedded? For example, if I construct a model of an adsorbate on a mineral surface, where that adsorbate has a full complement of 1st shell coordinating OH, O, and H2O groups as appropriate, but if I do not include all the uncoordinated f water atoms that would be nearby (so that I essentially have a surface in vacuum), will the potentials for my central atom be calculated correctly (or correctly enough for use in IFEFFIT)? a more specific example: the AsO4 tetrahedron bonded to the goethite surface, which is made of octahedrally-coordinated iron. The arsenate bonds to the goethite by sharing 1 edge of the tetrahedron with the apices of 2 adjacent Fe octahedra. a related question that comes to mind: if I just wanted to see the signal from the 2 adjacent Fe atoms, could I create a perfectly useable FEFF model (for IFEFFIT) by limiting my calculations to the small cluster of 1 arsenate tetrahedron and 2 Fe octahedra? thanks, andrea ~~ Andrea L. Foster, Ph.D. U.S.G.S. WMESC 345 Middlfield Rd., MS 901 Menlo Park, CA 94025 T: 650-329-5437 F: 650-329-5491 ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Re: [Ifeffit] inquire for the EXAFS of the mixture of species
Hi winejia, it is trivial but at the same time hard problem to solve. There are 2 ways: using Athena and using Artemis Using Athena you have measured your sample and all possible references. The result comes from the fit of the linear combination of your references. Using Artemis is similar but instead of measured references you create models (FEFF cards) from known structures and than fit to your experimental data. For sure you will find some more tricks in the archive of this mailing group. good luck kicaj W dniu 12-03-08 05:47, winejar8324 pisze: Hello everyone, I have a puzzle during analyzing of my EXAFS data. can someone please help me: I have a set of EXAFS data on solution sample at different pH. I wish to extract the structure information from the EXAFS region to accont for the reaction machanism. However, there are several configurations(as indicated by XANES) and species(as indicated by thermodynamics caculation) in solution due to the metal-Ligand complex balance. How can i obtain the structure information about this complex system from the EXAFS data? Thanks, winejia ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
