多体相互作用对固氖物态方程的影响

摘要

Based on the atomic cluster theory and multi-body expansion method ,this study ,taking ab initio Hartree-Fock self consistent field technique in the atomic distance of 1 .65 ~3 .00Å, calculates and re-searches the effects that the multi-body interactions energy which include two-body,three-body and four-body interactions have on the equation of state of face-centered cubic ( fcc) solid neon.The results are shown that many-body expansion potential was an exchange convergent series , and the even many-body contributions to the cohesive energy were repulsive ,whereas the odd many-body contributions to the cohe-sive energy were attractive .When the atomic distance is R≥2 .60Å, the interaction energy may be well described by two-body interactions .The atomic distance is between 1 .80Å~2 .60Å,the three-body con-tribution in many-body expansion potential should be taken into consideration .Below 1 .80Å, the four-body contributions have to be included .The calculated isotherm is in good agreement with the experimen-tal value in the experimentally studied ranges of pressures (0~208GPa) considering the two-body and three-body potentials,taking into account the four-body potential the pressure has been reached 240GPa. However it can be accurately explain the phenomenon of the present experiment at above 240 Gpa consid-ering the five-body potential .%基于原子团簇理论与多体展开方法，运用从头算自洽场方法计算固氖面心立方结构（ fcc）最邻近原子间距在1．65～3．00Å之间的两体、三体和四体相互作用能及其对物态方程的影响。结果表明：原子势能的多体展开级数是一交错级数，其中偶数体势对原子势的贡献为正，奇数体势对原子势的贡献为负；在R≥2．60Å的区间原子势能的多体展开式只需考虑两体势即可，在1．80≤R＜2．60Å的区间里原子势能的多体展开式需要考虑到三体势的贡献，在R＜1．80Å的区间原子势能的多体展开式需要考虑到四体势的贡献；只考虑两体相互作用时固氖的压缩特性表现过硬，考虑三体相互作用后基本上与实验结果吻合，压强范围已经达到目前的实验数据值（0～208GPa），考虑到四体相互作用后对压强研究区间已经达到240GPa，而在高于240GPa以上的压强区域需要考虑更高多体相互作用才能准确地解释。