多体相互作用对固氩物态方程的影响

采用ab initio自洽场(SCF)HFD方法及原子团簇理论,运用Gamess程序定量地计算了最近邻原子间R=2.40-4.00间高压下fcc晶体固氩的两体、三体结合能及物态方程.对原子势能多体展开式的收敛性和截断性做了分析说明.结果显示,固氩在高压区域,两体势对结合能的影响是正的,而三体势对结合能的影响则是负的.在高压区域,两体势对固氩的结合能贡献了过多的排斥效应,加入三体分量的修正后,理论计算能够较好地解释到80GPa的压强.

Effect of many-body interactions on the equation of state for Solid Argon

By using ab initio self-consistent field Hartree-Fork methods and atomic clusters expanding theory and employing Gamess program, two- and three-body interaction energies and the equation of state for solid argon in fcc crystal have been quantificationally calculated at the neighboring atomic distance R=2.40 -4.00 Å under high pressure. In addition, the convergence and truncation of atomic energy multi-body expansion are analyzed. It is found that two-body contribution to the cohesive energy is positive, while the three-body contribution is negative in solid argon under high pressure. At high pressure, only the consideration of the two-body contribution will overestimate the cohesive energy, hence it is necessary to introduce the three-body negative effects. The phenomenon of the experiment under 80GPa can be explained by considering the three-body potential.