Molecular Dynamics Simulation of Homogeneous Nucleation of Melting in Superheated Sodium Crystal

Abstract

The equilibrium melting process of perfect Na crystal and the homogeneous nucleation of melting in superheated Na crystal are simulated by the molecular dynamics method with EAM/FS many-body potential in this paper. Firstly, the equilibrium melting process of perfect Na crystal is simulated and compared with experiments and other potential (LJ (5-4) potential and mean force potential) simulations in literature. The results show that the equilibrium melting point of Na is about 414 K, close to the experimental value of 371 K, and the relative deviation is around 11.6 %. The simulated densities of Na match well with the experimental values within 300 K-700 K, and the largest relative deviation is about 2.05 %. It is indicated that the adopted EAM/FS potential is suitable for simulating the melting process of Na. Secondly, the homogeneous nucleation of melting in superheated Na crystal is simulated, and the homogeneous nucleation rate and kinetic stability limit are analyzed. It is found that the calculated critical radius and critical work of nucleation of homogeneous melting in superheated Na crystal decrease with increasing temperature. The nucleation rate of homogeneous melting in superheated Na crystal rises exponentially with increasing temperature, which is consistent with the expectation in the literature. The kinetic stability limit calculated for superheated Na crystal is 468.3 K, about 1.13 times the equilibrium melting point. The relation between the self-diffusion coefficient and temperature is also given as the Arrhenius form expression of Na. The fitted formula between the homogeneous nucleation rate and temperature is presented.

Keywords: Sodium, Molecular dynamics simulation, Equilibrium melting, Homogeneous nucleation