Effects of Inner-Core 2p States on Melting Curve and Structure of Dense Sodium at High Pressures(Condensed matter: structure and mechanical and thermal properties)

概要

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We have carried out ab initio molecular-dynamics (MD) simulations of dense liquid/solid sodium for 3s- and 2p3s-valence-electron models, and for different valence electron-ion interactions at high pressures. We have found that the melting curve has a melting point maximum, which depends on the type of valence-electron models used at high pressures. We have shown that, if we consider inner-core 2p states, the repulsive interatomic force becomes stronger and the pressure and temperature of the maximum melting point increase. We have investigated the effect of inner-core 2p states on the structure of liquid sodium, and found that, though the differences in the structures obtained with different valence-electron models are negligible in a relatively low-pressure region, the differences are significant at extremely high pressures, since inner-core 2p states play important roles at high pressures. We have also shown that the ultrasoft pseudopotential method and projector augmented-wave method give almost the same results.
社団法人日本物理学会の論文
2008-06-15