A Coupled Cluster Approach to the Electron Correlation Problem Using a Correlated Reference State
A Coupled Cluster Approach to the Electron Correlation Problem Using a Correlated Reference State
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DOI：
10.1007/978-1-4615-1937-9_12
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
D. Mukherjee
中科院分区：
文献类型：
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作者：
D. Mukherjee
耦合团簇（CC）形式主义，1，2从一个单一的参考函数开始，已经非常成功地处理电子相关的封闭壳层系统。3几个概括，包括多参考函数，导致CC理论的开壳层，已建议在最近几年4的框架内的有效哈密顿量，这提供了有趣的可能性，直接计算能量差异的光谱利益。虽然最初是为完整的模型空间设计的，但已经发现有必要为不完整的模型空间发展开壳层CC理论，因为否则经常有入侵者问题的危险。如果使用不完整的模型空间，入侵者似乎可以在很大程度上避免光谱能量差异，但它们仍然是计算势能面的真实的威胁，因为对于表面的不同区域存在不同的入侵者。
The Coupled Cluster (CC) formalism,1,2starting from a single reference function, has been eminently successful for treating electron correlation for closed shell systems.3Several generalizations to encompass multireference functions, leading to CC theories for open-shells, have been suggested in recent years4in the framework of effective hamiltonians, which have offered interesting possiblities of computing directly energy differences of spectroscopic interest. Although originally designed for complete model spaces,5it has been found necessary to develop the open-shell CC theory for incomplete model spaces4,6since otherwise there is often the danger of theintruder problem.It appears that the intruders can to a large extent be avoided for spectroscopic energy differences if one works with incomplete model spaces, but they remain a real menace for computing potential energy surfaces, since there are different intruders for the different regions of the surface.