ICAMS / Interdisciplinary Centre for Advanced Materials Simulation


Bond-order potentials for the bcc transition metals niobium and tungsten

Date: 16.03.2011
Place: DPG Spring Meeting 2011, Dresden, Germany

Miroslav Čák
Thomas Hammerschmidt
Ralf Drautz

Bond-order potentials (BOPs) are based on the tight-binding approximation for determining the energy of a system of many interacting atoms. The BOPs provide comparable accuracy as tight-binding at less computational cost and for better scaling behavior. While the previously developed BOPs involve numerical evaluation of the response (Green’s) function, the expressions for bond energy and interatomic forces are analytical within the formalism of the analytic BOPs. In this contribution, we present the parameterisation 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 very good transferability of our analytic BOPs to atomic structures of experimentally relevant complexity.

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