Köhn Andreas, Richings Gareth W, Tew David P
Institut fur Physikalische Chemie, Universität Mainz, Mainz, Germany.
J Chem Phys. 2008 Nov 28;129(20):201103. doi: 10.1063/1.3028546.
An implementation of the full explicitly correlated coupled-cluster singles and doubles model CCSD-F12 using a single Slater-type geminal has been obtained with the aid of automated term generation and evaluation techniques. In contrast to a previously reported computer code [T. Shiozaki et al., J. Chem. Phys. 129, 071101 (2008)], our implementation features a reduced dependence on the auxiliary basis set due to the use of a reformulated evaluation of the so-called Z-intermediate rather than straight forward insertion of an auxiliary basis expansion, which allows an unambiguous comparison to more approximate CCSD-F12 models. First benchmark results for total correlation energies and reaction energies indicate an excellent performance of the much cheaper CCSD(F12) model.
借助自动项生成和评估技术，已实现了使用单个斯莱特型双电子基函数的完全显式相关耦合簇单双激发模型CCSD-F12。与之前报道的计算机代码[T. Shiozaki等人，《化学物理杂志》129, 071101 (2008)]相比，我们的实现由于使用了对所谓Z中间量的重新表述评估，而不是直接插入辅助基展开，从而减少了对辅助基组的依赖，这使得能够与更近似的CCSD-F12模型进行明确比较。总相关能和反应能的首批基准结果表明，成本低得多的CCSD(F12)模型具有出色的性能。
