Interatomic potentials for elastically isotropic crystals

We introduce a simple approach to fitting interatomic potentials to represent elastically isotropic solids, in order to make direct comparisons with the predictions of isotropic linear elasticity. The potentials are of the Finnis-Sinclair type and are parametrized to fit Au and Ag. Under uniaxial loading, it was shown that the solids modelled employing the ‘elastically isotropic’ potentials remain elastically isotropic for strains of 0.5% or less. The properties of the (001), (011) and (111) surfaces were determined and compared with those of elastically anisotropic Au and Ag. It was also found that the surface energy anisotropy is lower in solids modelled employing 'elastically isotropic' potentials than in those represented by elastically anisotropic potentials.