Hanrath Michael
Institute for Theoretical Chemistry, University of Cologne, Cologne, Germany.
J Chem Phys. 2008 Apr 21;128(15):154118. doi: 10.1063/1.2899645.
This article reports on the convergence of the exponential multireference wavefunction Ansatz (MRexpT) [J. Chem. Phys. 123, 84102 (2005)] and the single-reference based multireference coupled cluster Ansatz [J. Chem. Phys. 94, 1229 (1991)] with respect to higher cluster excitations. The approaches are applied to the H(4), P(4), and BeH(2) model systems according to the recently published analysis by Evangelista et al. [J. Chem. Phys. 125, 154113 (2006)]. The results show both MRexpT and SRMRCC to be highly accurate although SRMRCC shows problems due to its lack of Fermi vacuum invariance (symmetry breaking).
本文报道了指数多参考波函数近似（MRexpT）[《化学物理杂志》123, 84102 (2005)] 与基于单参考的多参考耦合簇近似 [《化学物理杂志》94, 1229 (1991)] 在更高簇激发方面的收敛情况。根据埃万杰利斯塔等人最近发表的分析 [《化学物理杂志》125, 154113 (2006)]，这些方法被应用于H(4)、P(4)和BeH(2)模型体系。结果表明，尽管由于缺乏费米真空不变性（对称性破缺），单参考多参考耦合簇近似（SRMRCC）存在问题，但MRexpT和SRMRCC都具有很高的精度。
