基于原子晶体构型的高压固氩中的多体相互作用

Many-body interaction of highly compressed solid argon based on atomic crystal configuration

X射线衍射实验显示固氩是面心立方(fcc)晶格结构,目前对晶体氩的研究只限于两体,三体以及四体相互作用势.本文利用多体展开方法和超分子单、双(三)重激发耦合簇理论(CCSD(T))对固氩fcc晶格结构的三体和四体的几何构型、几何参数、不同体积下所有三体和四体构型的势能以及各构型所占比例等几个方面进行了准确的量子化学计算.结果表明:所有三体构型中对总的三体势能贡献最大的是构型1、构型6、构型12和构型23;三体势及其交换部分和色散部分的计算结果与现有解析经验势在长程部分符合得非常好,但在短程部分有较小差异.所有的四体构形中对总的四体势能贡献最大的是构型1,构型2,构型4,构型5,构型7和构型8;四体势及其交换势部分和色散部分的计算结果尚无解析经验势可比较.利用这些特殊构型的相关数据并结合其它构型,可拟合出更准确的三体经验势函数及其参数,也为拟合四体经验势函数及其参数提供了重要的参考价值.

X -ray diffraction experiments shows that solid argon is a face -centered cubic crystal structure （fcc structure）. At present, crystal argon is studied involving two -, three - and four- body potentials. Using the many- body expansion method and the double cluster with full single and double excitations plus perturbative treatment of triples （ CCSD （T））, the properties of fcc structure for solid argon which include geometrical config- uration, geometrical parameters, potential energy of three - and four - body potentials and the proportion of all configurations at different volumes were accurately calculated. It is concluded that the configuration 1,6, 12 and 23 play most important role in all three - body potential configurations. The calculation results of three - body po- tential, exchange potential and dispersion potential are in good agreement with the analytic experience potential in long - range part, but have small differences in short - range part. The configuration 1,2, 4, 5,7 and 8 play very important role in all four - body potential configurations, and there is not analytic experience potential to compare between the calculated results of four - body potential, exchange potential and dispersion potential. U- sing the data of these special configurations in combination with other configurations can fit a more accurate three - body experience potential function and its parameters, and also provide important reference value about fit four -body experience potential function and its parameters.