Dresden 2011 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 28: Topical Session Electron Theory III

MM 28.2: Talk

Wednesday, March 16, 2011, 16:00–16:15, IFW A

Bond-Order Potentials for bcc Transition Metals Niobium and Tungsten — •Miroslav Cak, Thomas Hammerschmidt, and Ralf Drautz — ICAMS, Ruhr Universitat Bochum

Bond-order potentials (BOPs) are derived from the tight-binding approximation by expanding the density of states in local moments contributions. The BOPs provide comparable accuracy as tight-binding at less computational cost and a better scaling behavior. While the previously developed BOPs involve numerical evaluation of the response (Green’s) function, the expressions for the bond energy and related interatomic forces are analytical within the formalism of the analytic BOPs. In this contribution, we present the parametrisation of analytic BOPs for the bcc transition metals Niobium and Tungsten. The parameters were optimised for the equilibrium bcc structure and extensively tested for atomic environments far from equilibrium that have not been considered in the fitting procedure. These tests include structural energy differences for competing structures; tetragonal, trigonal, hexagonal and orthorhombic deformation paths; formation energies of point defects and phonon dispersion relations. Comparison of these calculations with corresponding calculations using density-functional theory and numerical BOPs demonstrates a very good transferability of our analytic BOPs to atomic structures of experimentally relevant complexity.