Simulation of properties of liquid alkali metals at high temperatures and pressures by ab initio molecular dynamics method

摘要

The properties of liquid alkali metals Na and Cs over the entire temperature range of the existence of liquid state are investigated for the first time by the ab initio molecular dynamics (AIMD) method. The simulation was performed using the SIESTA software package. A pseudopotential is selected, and a model of liquid metal is constructed for a supercell with the number of atoms being 54, 250, and 1024. The total energy, heat capacity, diffusion coefficient, radial distribution function of atoms, and density of electron states are calculated. The temperature dependence of the heat capacity upon approaching the critical point manifests a feature correlating with the experimentally observed one, while the density of electron states has substantial deviations from the model of almost free electrons. It is shown that the AIMD method selected makes it possible to evaluate the melting point.