高温高密度条件下氮分子三体关联效应与冲击压缩特性

Three-Body Interactions and Shock Compression Properties of Condensed Nitrogen

基于量子化学从头计算方法,计算了处于高密度条件下氮分子之间的两体排斥势和三体关联势,并采用球面平均近似求得了它们各自的高温平均势能值,得到了包括三体关联效应的等效两体势函数与分子间距的解析关系。借助分子流体微扰变分理论,并考虑van derWaals长程作用,分别采用总平均两体势和总等效两体势,计算了液氮的冲击压缩曲线。计算结果表明,在不需要考虑分子离解的压缩范围内(1~35 GPa),三体关联效应的贡献使分子间总等效两体势函数比单独两个分子间总平均作用势函数明显软化,与实验Hugoniot数据结果一致。

Based on ab initio calculation of quantum-chemical theory,the repulsive potential among three nitrogen molecules(N2)3,as well as that between two nitrogens(N2)2,were calculated for a large amount of molecular directions from randomly sampling.The molecular distance and the geometry of the considered(N2)3 count the multi-body correlations in condensed nitrogen,and spherically averaged approximation of the orientation described the effect of high temperature.An analytic formula of the effective pair potential...