基于第一性原理的固氦零点振动能的量子理论计算

基于第一性原理，运用原子团簇理论和Hartree-Fock Self-Consistent-Field从头算法计算了高压固氦hcp结构在平衡位置r=1.75-2.6Å附近的原子相互作用能，并使用1stOpt软件拟合出固氦的零点振动频率，得到零点振动能、Gruneisen系数及零点振动压强，最后与实验值做了比较.结果表明：固氦晶体在其各自平衡位置附近的运动可近似为简谐振动；固氦晶体的零点振动频率随着摩尔体积的增大而减小；零点振动能占多体相互总能的比例超过5%，已不可忽略，其比例随摩尔体积的增加而增大；零点振动能随原子间距和摩尔体积的增大而减小;Gruneisen系数随着摩尔体积的增大而增大，并始终处于1和2之间；零点振动引起的压强与实验值曲线趋势完全一致，但比实验值稍小，零点振动压强对总压强的贡献随着摩尔体积的增大由8%增大到50%左右，由此引起的零点振动压强值的贡献越来越大.

Quantum Calculation Based on the First-principles for the Zero-point Vibration Energy of Solid Helium

Based on the First-principles, the atomic interaction energy of solid helium were calculated using ab initio calculation Hartree-Fock Self-Consistent-Field method and the atomic clusters theory in the atomic distance of 1.75-2.60Å. It is also obtained that the zero-point vibration frequency, the zero-point vibration energy, Gruneisen coefficient and the zero-point vibration pressure by 1stOpt software. Finally, our results were compared with the experimental results. These conclusions can be drawn that the motion of solid helium can be approximate to simple harmonic vibration in their equilibrium position; The zero-point vibration frequency of solid helium decreases with the increase of the molar volume; The proportion of the zero-point vibration energy and the total many-body interaction energy is more than 5% for solid neon, it can not be ignored and increases with the increase of the molar volume; The zero-point vibration energy decreases with the increase of the molar volume and the atomic distance; With the increase of the molar volume, Gruneisen coefficient increase, and its value is always between 1 and 2; The curve of zero-point vibration pressure has a similar tendency with the reported experimental results, but it is slightly smaller than the experimental results; With the increase of the molar volume, the zero-point vibration pressure contribution to the total pressure increased from 8% to 50%, and it has played an increasingly important role in the total pressure.