Multireference perturbation configuration interaction V. Third-order energy contributions in the Moller-Plesset and Epstein-Nesbet partitions
Multireference perturbation configuration interaction V. Third-order energy contributions in the Moller-Plesset and Epstein-Nesbet partitions
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DOI：
10.1007/s00214-002-0336-z
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发表时间：
2002-05-01
影响因子：
1.7
通讯作者：
Cimiraglia, R
中科院分区：
文献类型：
--
作者：
Angeli, C;Cimiraglia, R
给出了三阶微扰理论应用于多参考零阶波函数的一种简单实现。考虑了哈密顿量的两种不同划分(Moller-Plesset重心和Epstein-Nesbet)。对CH2和N-2两个测试用例进行了检验。三阶结果在任一划分中都表现出良好的一致性，并且总体上相对于二阶结果是改进的。在爱泼斯坦-内斯贝中没有的入侵态现象，在穆勒-普列塞特划分中似乎被放大了。
A simple implementation of third-order perturbation theory applied to a multireference zero-order wavefunction is presented. Two different partitions of the Hamiltonian (Moller-Plesset baricentric and Epstein-Nesbet) are considered. Two test cases, CH2 and N-2, are examined. The third-order results are shown to be in good agreement in either partition and are generally an improvement with respect to the second-order results. The phenomenon of intruder states, absent in Epstein-Nesbet, appears to be magnified in the Moller-Plesset partition.