Molecular dynamics simulation on plasma phase transition of aluminum single crystal under extreme conditions

The electron force field is a new molecular dynamics method which combines the quantum mechanics and the classical molecular dynamics and has the ability of computing systems with electrons explicitly over multi-picoseconds time scales and 10⁴ atoms space scales. The effective core pseudo-potential method is introduced in order to overcome the problem that the electron force field is only suitable for the system containing s electrons while is incapable to solve the system including p and d electrons. The plasma phase transition of aluminum single crystal under static extreme conditions and hypervelocity impact is investigated by exploring the electric force field in conjunction with the effective core pseudo-potential method. The typical snap of plasma phase transition and the relationship between the ionization percent and temperature under static extreme conditions are obtained. The micro-structure of the shock front in the aluminum single crystal is presented in detail, and the ionized electrons appear in the compressed region. The Hugoniot relationship is obtained by simulating the shock processes under various shock wave velocities, and the simulated results agree well with the experimental data. The characteristic of plasma induced by the hypervelocity impact is also studied based on the ionization percent. The results show that the ionization percent increases with the shock strength and the reflect wave has a negative effect on the ionization of the electrons. The current study indicates that the electron force field in conjunction with the effective core pseudo-potential method has a good ability of computing the plasma phase transition of material under static extreme conditions and hypervelocity impact.