Molecular Dynamics Studies of Solid-Liquid Interface of Soft-Core Model

Abstract

The (100) solid-liquid coexistent state and the interface are studied by a molecular dynamics method for the soft-core system with the pair potential φ(r)=ε(σ⁄r)¹². To reduce computing time damping and random forces satisfying the fluctuation-dissipation theorem are applied to each atom during equilibration of the system. Transition parameters are obtained rather easily. which are in agreement with other works. This means, however, that monitoring transition parameters is not enough for judging to what degree a simulated state is approaching to a coexistent equilibrium state. The interface is not very stable and proceeds or recedes according to local density and temperature fluctuations. Therefore, averaged features depend on time intervals over which time averages are taken. An apparently large thickness of the interface observed for a LJ system is interpreted in this way. Feasibility of simulating crystallization process is also shown.