An engineering-oriented embedded-atom-method potential fitting procedure for pure fcc and bcc metals

Abstract

A numerical fitting procedure for developing embedded-atom-method (EAM) potentials for pure fcc and bcc metals is presented in this paper. The focus is on developing an approximate EAM potential that suffices for engineering applications to pure metals. The EAM inter-atomic potential consists of two parts: the pair-potential and the embedding function. By assuming a parameterized form for the pair-potential, the embedding function is numerically fit into the hydrostatic linear-elastic stress equations of the metal at hand. Following this, the single crystal anisotropic Young's modulus and Poisson's ratio of the metal are calculated through a uniaxial molecular dynamics (MD) simulation, and are compared to experimental values. The parameter of the pair-potential is then changed and the embedding function recalculated until the Young's modulus and Poisson's ratio are satisfactorily predicted. Following this, a parameterized relation between temperature and kinetic energy is fit into the thermal expansion data of the metal, and a temperature dependent volume factor for calculating Young's modulus at 0 and 100 K accurately is numerically fit. Finally, the potential is adjusted without changing the slopes (i.e. forces) to fit the cohesive energy of the metal. The resulting EAM potential for pure copper is tested to see how accurately the thermal and elastic properties of single crystal copper are predicted. The thermal and elastic properties are found to be predicted accurately. This shows that the EAM potential fitting procedure thus developed is suitable for atomic-level engineering applications.