N Dimakis et al 2009 J. Phys.: Conf. Ser. 190 012011 doi:10.1088/1742-6596/190/1/012011
N Dimakis1,3, T Mion1 and G Bunker2
Show affiliationsWe present an accurate and efficient technique for calculating thermal X-ray absorption fine structure (XAFS) Debye-Waller factors (DWFs) applicable to crystalline materials. Using Density Functional Theory on a 3×3×3 supercell pattern of MnO structure, under the nonlocal hybrid B3LYP functional paired with Gaussian local basis sets, we obtain the normal mode eigenfrequencies and eigenvectors; these parameters are in turn used to calculate single and multiple scattering XAFS DWFs. The DWFs obtained via this technique are temperature dependent expressions and can be used to substantially reduce the number of fitting parameters, when experimental spectra are fitted with a hypothetical structure. The size of the supercell size limits the R-space range that these parameters could be used. Therefore corresponding DWFs for paths outside of this range are calculated using the correlated Debye model. Our method is compared with prior cluster calculations and with corresponding values obtained from fitting experimental XAFS spectra on manganosite with simulated spectra.
78.70.Dm X-ray absorption spectra
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
71.20.Ps Other inorganic compounds
63.70.+h Statistical mechanics of lattice vibrations and displacive phase transitions
Issue 1 (2009)
N Dimakis et al 2009 J. Phys.: Conf. Ser. 190 012011
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