Cuervo Javier Eduardo, Roy Pierre-Nicholas
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
J Chem Phys. 2006 Sep 28;125(12):124314. doi: 10.1063/1.2352735.
We use the path integral ground state method to study the energetic and structural properties of small para-H2 clusters of sizes ranging from 2 to 20 molecules. A fourth order formula is used to approximate the short imaginary-time propagator and two interaction potentials are considered. Our results are compared to those of exact basis set calculations and other quantum Monte Carlo methods when available. We find that for all cluster sizes considered, our results show a lower ground state energy than literature values obtained by diffusion Monte Carlo and variational Monte Carlo. For the dimer and trimer, ground state energies are in good agreement with exact results obtained using the discrete variable representation. Structural properties are found to be insensitive to the choice of interaction potential. We explore the use of Pekeris coordinates to analyze the importance of linear arrangement in trimers and for trimers within clusters of larger size.
我们使用路径积分基态方法来研究大小从2到20个分子的小的仲氢（para-H₂）团簇的能量和结构性质。采用四阶公式来近似短虚时传播子，并考虑了两种相互作用势。当有可用数据时，我们将结果与精确基组计算结果以及其他量子蒙特卡罗方法的结果进行比较。我们发现，对于所考虑的所有团簇大小，我们的结果显示出比通过扩散蒙特卡罗和变分蒙特卡罗获得的文献值更低的基态能量。对于二聚体和三聚体，基态能量与使用离散变量表示法获得的精确结果吻合良好。发现结构性质对相互作用势的选择不敏感。我们探索使用佩克里斯坐标来分析三聚体中线性排列的重要性以及更大尺寸团簇内三聚体的情况。
