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A dynamic-charge, many-body potential function is proposed for the hafnium/hafnium oxide system. It is based on an extended Tersoff potential for semiconductors and the charge-optimized many-body potential for silicon oxide. The materials fidelity of the proposed formalism is demonstrated for both hafnium metal and various hafnia polymorphs. In particular, the correct orders of the experimentally observed polymorphs of both the metal and the oxide are obtained. Satisfactory agreement is found for the structural and mechanical properties, defect energetics, and phase stability as compared to first-principles calculations and/or experimental values. The potential can be used in conjunction with the previously determined potentials for the Si and SiO 2 system. This transferability is demonstrated by comparing the structure of a hafnia/silicon interface to that previously determined from electronic-structure calculations.

Presented is a charge optimized many body potential (COMB) for metallic copper and copper oxide systems based on an extended Tersoff formalism coupled with variable charge electrostatics. To faithfully reproduce interactions between molecular oxygen and the metal surface, the potential includes atomic polarizabilities via both a point dipole model and dynamic partial charges, both of which are equilibrated through an extended Lagrangian scheme. The potential is fit to a training set composed of both experimental and ab initio computational data for cohesive energies, formation enthalpies, elastic properties and surface energies of several metallic and oxide phases as well as bond dissociation energies for molecular oxygen and several of its anions. The potential is used in molecular dynamics simulations to model the Cu(111)||Cu 2 O(100) interface and the oxidation of the Cu(100) surface.

Abstract

A classical interatomic potential for uranium metal is derived within the framework of the charge optimized many body (COMB) formalism. The potential is fitted with a database obtained from experiment and density functional theory (DFT) calculations. The potential correctly predicts orthorhombic α-U to be the ground state. Good agreement with experimental values is obtained for the lattice parameters, nearest neighbor distances, and elastic constants. Molecular dynamics simulations also correctly show the anisotropy in the coefficient of thermal expansion and the temperature dependence of the nearest neighbor distances.