高压固氩物态方程的量子理论计算  

Quantum Calculation for Equation of State of Compressed Solid Argon

作　　者：郑兴荣[1] 陈海军[1] 高晓红[1] 李继弘[1] 宋小永 

机构地区：[1]陇东学院电气工程学院,甘肃庆阳745000

出　　处：《高压物理学报》2017年第4期396-402,共7页Chinese Journal of High Pressure Physics

基　　金：国家自然科学基金(11565018);陇东学院青年科技创新项目基金(XYZK1501)

摘　　要：基于第一性原理,运用ab initio超分子单、双(三)重激发耦合簇理论(CCSD(T))和aug-cc-pVQZ基矢,精确计算了fcc晶体固氩在最近邻原子间距R=0.20~0.39nm时的两体、三体和四体结合能,零点振动能及物态方程。结果表明:固氩的多体势对结合能的贡献在高压区域是一正负交叉级数;零点振动能占多体相互总能的比例较小,但不可忽略;在高压区域,只考虑两体势时对固氩的压缩特性表现过硬,加入三体势后与实验结果在60GPa内完全吻合,考虑到四体势后对整个实验区间0~114GPa内做出令人满意的描述,且在压强达到114GPa时与实验值相差约3GPa,吻合程度达到97%。最后,通过与密度泛函理论的局域密度近似和广义梯度近似方法比较发现,泛函理论(DFT)只有在50~114GPa范围内与实验值符合较好,不如本研究所采用方法适用的压强范围宽。Based on the first-principles and using the double cluster with full single and double excitations plus perturbative treatment of triples （CCSD（T）） and the aug-cc-pVQZ basis set,many-body contributions to the cohesive energy, the zero-point vibration energy and the equation of state of solid argon were accurately calculated with the atomic distance R from 0. 20 nm to 0.39 nm under high pressure. The results show that the contribution of the many-body interaction to the cohesive energy is an exchange convergent series, and the proportion of the zero-point vibration energy in the total energy is small but by no means negligible. Under high pressure, the compression characteristics of solid argon is over-hardened when only the two-body interaction is considered. By introducing the three-body interaction, the maximum pressure under which our calculations make a satisfactory description of the experiment data can reach 60 GPa. Further,when the four-body interaction is taken into account, the application scope will be expanded to 0-114 GPa. At 114 GPa,the difference between our calculation and that of the experiment is only about 3 GPa, and the relative error is merely 3%. Besides, this work has a broader application scope than the density functional theory, which at present shows a good agreement with the experimental result only in the pressure range of 50-114 GPa.

关 键 词：固氩 超分子单、双(三)重激发耦合簇理论 多体结合能 零点振动能 物态方程 

分 类 号：O641[理学—物理化学] O561.1[理学—化学]