Theoretical study on the structure and dynamics of liquids which show metal-nonmetal transitions

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In this research project we have carried out simulation studies to clarify the microscopic mechanism of metal-nonmetal transitions in liquid metals by investigating the structural and dynamical properties of these liquids. We have studied and clarified the following problems :(1)The static structure of nonmetallic fluid mercury near the critical point is known to be well described by the effective Lennard-Jones-type pair potential. We have investigated the dynamic structure of fluid mercury near the critical point by the molecular-dynamics (MD) simulations using the effective pair potential and shown that the dynamical structure factor, the dispersion relation and the sound velocity are also well described in comparison with the recent inelastic x-ray scattering experiments.(2)It is known that there occurs a first-order liquid-liquid phase transition in liquid phosphorus at high temperatures and high pressures. We have studied the dynamical properties of such liquid phosphorus by ab initio MD simulations and found the vibration mode of P_4 molecules and the sound velocity, which are suggestive for future experiments.(3)We have investigated the pressure-induced changes in the structure and electronic states of liquid carbon, and clarified the microscopic mechanism of the pressure-induced structural change, in particular the origin of the maximum melting point.(4)We have investigated by ab initio MD simulations the structure and electronic states of liquid mixtures such as liquid In_2Te_3 and As_2S_3 to clarify the mechanism of semiconductor-metal transition.(5)We have studied the structural and electronic properties of group 14 liquid mixtures such as liquid Ge-Sn and Ge-Si alloys by ab initio MD simulations.