Molecular dynamics study of melting of the bcc metal vanadium. II. Thermodynamic melting

We present molecular dynamics simulations of the thermodynamic melting transition of a bcc metal, vanadium, using the Finnis-Sinclair potential. Our motivation was to answer the question whether premelting phenomena, extensively studied for fcc metals, are also present in bcc metals. We studied the structural, transport, and energetic properties of slabs made of 27 atomic layers with a free surface. We investigated premelting phenomena at the low-index surfaces of vanadium, V(111), V(001), and V(011), finding that as the temperature increases, the V(111) surface disorders first, then the V(100) surface, while the V(110) surface remains stable up to the melting temperature. Also, as the temperature increases, the disorder spreads from the surface layer into the bulk, establishing a thin quasiliquid film in the surface region. We conclude that the hierarchy of premelting phenomena is inversely proportional to the surface atomic density, being most pronounced for the V(111) surface which has the lowest surface density.