Heat Capacity and Gruneisen Parameter for GaN with Zinc-Blende Structure

A shell model molecular dynamics method is used to investigate the behavior of the pressure-volume relationship, heat capacities at constant pressure and constant volume, Gruneisen parameter for GaN with zinc-blende cubic structure at high pressures and high temperatures. The interactions between Ga-Ga, Ga-N, and N-N are described with polarizable potential models which have assigned two different partially ionic charges to Ga and N by taking into account of the ionic character of GaN. It is shown that the calculated thermodynamic parameters at ambient condition are in good agreement with the available theoretical results. Compared with the results from first-principles calculations, the discrepancy of constant-volume heat capacity at lower temperature may be explained well with different approximation mechanisms. The properties of GaN with zinc-blende structure are summarized in the temperature range of 300-2000 K and pressure up to 40 GPa.