Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 55: Theoretical methods II
O 55.2: Vortrag
Mittwoch, 28. März 2012, 17:00–17:15, MA 043
DFT based tight-binding with environment-dependent crystal field splittings — •Alexander Urban1, Matous Mrovec2, 3, Christian Elsässer2, 3, and Bernd Meyer1 — 1ICMM/CCC, University of Erlangen-Nürnberg — 2Fraunhofer IWM, Freiburg — 3IAM-ZBS, Karlsruhe Institute of Technology
In traditional tight-binding (TB) models the intra-atomic (on-site) matrix elements of the Hamiltonian are approximated by constant atomic values and crystal field splittings are neglected. Using our recently developed scheme for deriving TB bond and overlap integrals from DFT calculations of arbitrary reference configurations it is, however, easy to analyze also the on-site integrals [1]. We find that the values of these matrix elements may depend strongly on the atomic environment, and neglecting the crystal field splittings introduces significant errors in the electronic structure. A new crystal field TB (CF-TB) scheme will be presented which allows to take the environmental dependence of the on-site terms into account [2]. The parameters for this straightforward extension of the Slater-Koster rules are readily accessible using our projection framework [1]. Comparisons of the CF-TB band structures and densities of states for a representative set of benchmark cases with DFT reference results demonstrate an enhanced transferability of the CF-TB parametrization.
[1] A. Urban, M. Reese, M. Mrovec, C. Elsässer, B. Meyer, Phys. Rev. B 84 (2011) 155119
[2] A. Urban, M. Mrovec, C. Elsässer, B. Meyer, in preparation