Coupled-cluster methods including noniterative corrections for quadruple excitations -: art. no. 054101
Coupled-cluster methods including noniterative corrections for quadruple excitations -: art. no. 054101
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DOI：
10.1063/1.1950567
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发表时间：
2005-08-01
影响因子：
4.4
通讯作者：
Gauss, J
中科院分区：
文献类型：
--
作者：
Bomble, YJ;Stanton, JF;Gauss, J
本文提出了一种处理耦合集团理论中四重激发效应的新方法。在该方法中，四重激发的贡献计算从一个公式的基础上的非厄米特微扰理论类似于以前使用的证明通常的非迭代的三重校正中使用的耦合集群单打和双打方法与微扰治疗的三重激发（CCSD（T））。本文所讨论的方法通过增加四重激发的微扰处理（CCSDT（Q）），在改进全耦合团簇单、双、三重方法（CCSDT）获得的能量方面起着平行的作用。该方法进行了测试的一组广泛的例子，并显示出提供的总能量相比，有利的与完整的单打，双打，三重和四重（CCSDTQ）的方法。(C)2005年美国物理学会。
A new method is presented for treating the effects of quadruple excitations in coupled-cluster theory. In the approach, quadruple excitation contributions are computed from a formula based on a non-Hermitian perturbation theory analogous to that used previously to justify the usual noniterative triples correction used in the coupled cluster singles and doubles method with a perturbative treatment of the triple excitations (CCSD(T)). The method discussed in this paper plays a parallel role in improving energies obtained with the full coupled-cluster singles, doubles, and triples method (CCSDT) by adding a perturbative treatment of the quadruple excitations (CCSDT(Q)). The method is tested for an extensive set of examples, and is shown to provide total energies that compare favorably with those obtained with the full singles, doubles, triples, and quadruples (CCSDTQ) method. (C) 2005 American Institute of Physics.