Investigating Multireference Character and Correlation in Quantum Chemistry
Investigating Multireference Character and Correlation in Quantum Chemistry
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DOI：
10.1021/acs.jctc.5b00543
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发表时间：
2015-09-01
影响因子：
5.5
通讯作者：
Paterson, M. J.
中科院分区：
文献类型：
--
作者：
Coe, J. P.;Paterson, M. J.
我们回顾了一系列的量子化学多参考诊断，并讨论他们的分子轨道的选择。我们展示了P. - O. Lowdin也可以被看作是通过相对于单个行列式的空间纠缠来量化电子关联。我们考虑三个例子系统从量子化学表现出三种不同的组合的多参考字符和相关性：不强多参考和不强相关，强多参考，但不强相关，强多参考与强相关。我们发现，一个多参考措施（MR）不改变实质性的截断用于Monte Carlo组态相互作用计算和调查使用自然轨道的效果。我们看到，一个耦合集群的单打和双打诊断和密度泛函理论诊断给出了正确的一般预测这些系统的多参考字符。我们还期待在收集的非相互作用的氢分子的多参考字符的问题和拉伸氢分子的多参考字符的基础大小的影响。
We review a range of multireference diagnostics for quantum chemistry and discuss them in terms of choices of the molecular orbitals. We show how an approach(1) of P.-O. Lowdin can also be viewed as quantifying the electron correlation via the spatial entanglement relative to a single determinant. We consider three example systems from quantum chemistry that exhibit three different combinations of multireference character and correlation: not strongly multireference and not strongly correlated, strongly multireference but not strongly correlated, and strongly multireference together with strong correlation. We find that a multireference measure (MR) does not change substantially with the cutoff used for a Monte Carlo configuration interaction calculation and investigate the effect of using natural orbitals. We see that a coupled-cluster singles and doubles diagnostic and a density-functional theory diagnostic give a correct general prediction of the multireference character for these systems. We also look at the issue of multireference character for a collection of noninteracting hydrogen molecules and the effect of basis size on the multireference character of a stretched hydrogen molecule.