Hi Jakob, As you have noted the fine structure in the projected DOS and the XAS is the same, so the relation between them is: XAS = gamma(E) LDOS, where gamma(E) = mu_0(E)/rho_0(E), where gamma(E) is a smoothly varying atomic-like quantity which is essentially a ratio of embedded atomic matrix elements. In systems with a white line $mu_0$ and hence, gamma(E) will likely be peaked at threshold. As a result the XAS is smoothly related to the LDOS with appropriate selection rules. This discussion assumes core-hole effects are small, and final state broadening is applied both the the LDOS and XAS. J. Rehr On Mon, 11 Dec 2006, Frommer Jakob wrote:
Dear all, I have a FEFF related question (I know that this is an IFEFFIT list, but I guess the subjects are closely related). I try to model some of my Cr XANES data with FEFF (following the procedure outlined in an excellent publication in Chem Phys 300 (2004) 13-22 � the authors have shown that it is possible to explain the Cr XANES spectra at least qualitatively by the means of FEFF calculations). I have however still some trouble to understand the difference (or the relation) between the XANES results given in the xmu.dat file and the l-projected density of states results (ldosXX.dat). Due to rho(E)=rho_0(E)[1+chi(E)] I would expect them to conincide (if the rho is calculated for the correct l � i.e. if the matrix element is non-zero). However I observed that the ldos and the xmu do not always coincide � is this possible? Furthermore at the white line position (from what I know, the white line is commonly interpreted as being due to the transition into unoccupied but bound states)! the xmu shows strong intensity whereas the ldos do not (maybe one comment: I assume that the e-scales in the ldos-file and in the xmu-file are the same). I am using FEFF8.2 with the SCF, DOS, XANES and FMS card. I would be obliged for your help. Thanks Jakob
P.s.: for hydroxide structures FEFF is always returning �bad counts� if I include the protons into the FEFF calculation � however this might be also due to bad input structures.
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Jakob Frommer Soil Chemistry Group Institute of Biogeochemistry and Pollutant Dynamics, ETH Z�rich Universit�tstrasse 16, CHN F19 CH - 8092 Z�rich Tel: +41 44 632 87 58 Fax: +41 44 633 11 18 Email: jakob.frommer@env.ethz.ch http://www.ito.ethz.ch/SoilChem/
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