利用Gordon-Kim模型对NaCl物态方程的研究

AN INVESTIGATION OF THE EQUATION OF STATE OF NaCl AT HIGH PRESSURE BY USE OF GORDON-KIM MODEL

本文从孤立离子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Gruneisen参数和物态方程,其结果与实验值符合程度是令人满意的。

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, thw 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.