Static And Dynamic Structures Of Liquid Tin At High Pressure From Ab Initio Molecular Dynamics

Static and dynamic structures of liquid Sn were studied by ab initio molecular-dynamics simulations from a state near the melting point (573 K, 0 GPa) to one at higher temperature and pressure (1273 K, 14 GPa). The calculated static structures are in good agreement with the experimental data for a wide range of temperatures and pressures. The dynamic structure factors also agree reasonably well with the available experimental data. Though a cage effect and a transverse mode exist near the melting point, they tend to fade out with increasing temperature. On the other hand, at high pressure, we found that the cage effect and the transverse mode recover even at high temperature. We have also confirmed that a mixing effect exists; that is, when a transverse collective mode occurs in liquid Sn, it also produces a longitudinal mode with a frequency similar to itself. This mixing effect is crucially important for experimental observations of transverse modes.