Pressure Dependence of Fusion Entropy and Fusion Volume of Six Metals

Abstract

Molecular dynamics simulations of the melting curves of six metals including Ag, Cu, Al, Mg, Ta, and Mo for the pressure range (0 to 15) GPa are reported. The melting curves of Ag, Cu, Al, and Mg fully confirm measurements and previous calculations. Meanwhile, the melting curves of Ta and Mo are consistent with previous calculations but diverge from laser-heated diamond-anvil cells values at high pressure. Our results suggest that the melting slope at 100 kPa is related to the electronic configuration of the element. In addition, the pressure dependence of fusion entropy and fusion volume are calculated up to 15 GPa. The overall fusion entropy is separated into topological entropy of fusion (ΔSD) due to the configuration change in melting and the volume entropy of fusion (ΔSV) due to the latent volume change in melting. Furthermore, we checked the R ln 2 rule under high pressure, according to which the value of ΔSD is a constant at ambient pressure. Result shows that the value of ΔSD is close to R ln 2 at ambient pressure and reflects a slow decrease when pressure increases.