An Investigation of the Equation of State of NaCl at High Pressure by Use of Gordon-Kim Model
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摘要: 本文对孤立离子Hartree-Fock波函数的数值解出发，直接计算了NaCl晶体中各种离子对的相互作用势。结果表明，对不同的离子对，其短程作用势性质不同。对Na+-Cl-离子对，其短程作用势为正，而对Cl--Cl-离子对和Na+-Na+离子对，对物理上感兴趣的大部分距离范围内，其短程作用势为负。在对以上的离子对势进行了解析拟合后，通过晶格动力学的方法计算了晶体的Grneisen参数和物态方程，其结果与实验符合程度是令人满意的。Abstract: Pair-potentials of ions in the NaCl crystal are calculated by using Gordon-Kim model and numerical solutions of Hartree-Fock wave functions for free ions. Results show that short range interactions have different properties for different pairs of ions, the cation-anion pair interaction potential is repulsive, but the cation-cation and anion-anion pair interaction potentials are attractive in the separation range of interest here. Different functional forms of these potentials are adopted and the parameters are determined by the least-square-fit. The Gruneisen parameter and the equation of state of NaCl are calculated by using the theory of lattice dynamics. Agreements between the calculated results and the experimental data are satisfactory.
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Key words:
- equation of state /
- high pressure /
- interionic potential
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