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Title: New Approach for 3D Local Structure Refinement Using Non-Muffin-Tin XANES Analysis

Abstract

A new technique of 3D local structure refinement using full-potential X-ray absorption near edge structure (XANES) analysis is proposed and demonstrated in application to metalloorganic complexes of Ni. It can be applied to determine local structure in those cases where the muffin-tin approximation used in most full multiple scattering schemes fails. The method is based on the fitting of experimental XANES data using multidimensional interpolation of spectra as a function of structural parameters, recently proposed by us, and ab-initio full potential calculations of XANES using finite difference method. The small number of required ab-initio calculations is the main advantage of the approach, which allows one to use computationally time-expensive non-muffin-tin finite-difference method. The possibility to extract information on bond angles in addition to bond-lengths accessible to standard EXAFS is demonstrated and it opens new perspectives of quantitative XANES analysis as a 3D local structure probe.

Authors:
;  [1];  [2]
  1. Faculty of Physics, Rostov State University, Rostov-on-Don, 344090 (Russian Federation)
  2. Institute of Molecules and Materials, University of Nijmegen, Nijmegen (Netherlands)
Publication Date:
OSTI Identifier:
21054758
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 882; Journal Issue: 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644436; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTRA; ABSORPTION SPECTROSCOPY; APPROXIMATIONS; BOND ANGLE; BOND LENGTHS; FINE STRUCTURE; FINITE DIFFERENCE METHOD; INTERPOLATION; MUFFIN-TIN POTENTIAL; MULTIPLE SCATTERING; NICKEL COMPOUNDS; ORGANOMETALLIC COMPOUNDS; X-RAY SPECTRA; X-RAY SPECTROSCOPY

Citation Formats

Smolentsev, Grigory, Soldatov, Alexander V., and Feiters, Martin C. New Approach for 3D Local Structure Refinement Using Non-Muffin-Tin XANES Analysis. United States: N. p., 2007. Web. doi:10.1063/1.2644436.
Smolentsev, Grigory, Soldatov, Alexander V., & Feiters, Martin C. New Approach for 3D Local Structure Refinement Using Non-Muffin-Tin XANES Analysis. United States. doi:10.1063/1.2644436.
Smolentsev, Grigory, Soldatov, Alexander V., and Feiters, Martin C. Fri . "New Approach for 3D Local Structure Refinement Using Non-Muffin-Tin XANES Analysis". United States. doi:10.1063/1.2644436.
@article{osti_21054758,
title = {New Approach for 3D Local Structure Refinement Using Non-Muffin-Tin XANES Analysis},
author = {Smolentsev, Grigory and Soldatov, Alexander V. and Feiters, Martin C.},
abstractNote = {A new technique of 3D local structure refinement using full-potential X-ray absorption near edge structure (XANES) analysis is proposed and demonstrated in application to metalloorganic complexes of Ni. It can be applied to determine local structure in those cases where the muffin-tin approximation used in most full multiple scattering schemes fails. The method is based on the fitting of experimental XANES data using multidimensional interpolation of spectra as a function of structural parameters, recently proposed by us, and ab-initio full potential calculations of XANES using finite difference method. The small number of required ab-initio calculations is the main advantage of the approach, which allows one to use computationally time-expensive non-muffin-tin finite-difference method. The possibility to extract information on bond angles in addition to bond-lengths accessible to standard EXAFS is demonstrated and it opens new perspectives of quantitative XANES analysis as a 3D local structure probe.},
doi = {10.1063/1.2644436},
journal = {AIP Conference Proceedings},
number = 1,
volume = 882,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}
  • A technique of three-dimensional (3D) local structure refinement is proposed and demonstrated by applying it to the metal complex Ni(acacR){sub 2}. The method is based on the fitting of experimental x-ray absorption near-edge structure (XANES) using a multidimensional interpolation of spectra and full potential calculations of XANES. The low number of calculations required is the main advantage of the method, which allows a computationally time-expensive method using a non-muffin-tin potential to be applied. The possibility to determine bond angles in addition to bond lengths accessible to extended x-ray-absorption fine structure opens new perspectives of XANES as a 3D structure probe.
  • The authors describe various aspects of electronic structure calculation for amorphous metals using the linear muffin-tin orbital (LMTO) scheme. They discuss calculations of the magnetic properties within the framework of multiple scattering formalism assuming collinear magnetic structure and using the linear muffin-tin orbital Green`s function method. Results for the effective exchange coupling parameters and local magnetic moments for amorphous Fe and Co are discussed with special emphasis on the dependence of these quantities on the local and global features of the structure. A method of calculating the electronic transport properties in transition metal glasses, based on the LMTO-recursion method andmore » the Kubo-Greenwood formula, is presented. The practical limitations of the method and the ways to overcome them are briefly discussed.« less
  • We report self-consistent-field calculations for the noble metals Cu, Ag, and Au. This work represents an improvement on previous work in that we have included both (self-consistently) non-muffin-tin terms in the crystal potential and relativistic effects in the kinematics (by solving the single-particle Dirac equation) and in the interactions (by employing a relativistic correction to the exchange-correlation potential). The significance of these improvements has been examined by a comparison with different versions of our own calculations with previous calculations, and by a comparison of experiments. An important result obtained is that the Fermi-surface discrepancy previously reported for Cu is greatlymore » reduced without the necessity of artificially increasing the strength of the exchange-correlation potential.« less
  • We report the results of a self-consistent relativistic augmented-plane-wave calculation of the electronic structure of Nb. This calculation was performed using potentials and charge densities of general shape; i.e., the muffin-tin approximations of a spherical shape inside the muffin-tin spheres and constant in the interstitial region were both removed. The results are thus an accurate representation of the Hohenberg-Kohn-Sham formalism for Nb. We find that the results are generally better than those obtained using the full Slater (..cap alpha.. = 1) overlapping-charge-density model. The effects of small changes in exchange parameter ..cap alpha.. and lattice constant a have also beenmore » calculated.« less
  • The effect of removing the muffin-tin approximation in a relativistic-augmented-plane-wave calculation of the electronic structure of Nb is described. The most significant effect found is that two experimentally observed orbits occur in a fully non-muffin-tin relativistic calculation which are not present in the muffin-tin calculation. The procedure for constructing the potential in the required form and the modifications to the secular equation are explicitly described. (AIP)