Coupled-Cluster Valence-Bond Singles and Doubles for Strongly Correlated Systems: Block-Tensor Based Implementation and Application to Oligoacenes.
Coupled-Cluster Valence-Bond Singles and Doubles for Strongly Correlated Systems: Block-Tensor Based Implementation and Application to Oligoacenes.
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DOI：
10.1021/acs.jctc.6b01092
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发表时间：
2017-01
影响因子：
5.5
通讯作者：
Joonho Lee;David W. Small;E. Epifanovsky;M. Head‐Gordon
中科院分区：
文献类型：
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作者：
Joonho Lee;David W. Small;E. Epifanovsky;M. Head‐Gordon
我们展示了基于块张量的耦合簇价键单键和双键（CCVB-SD）的实现[Small，D. W的;海德-戈登J.Chem.Phys.2012，137，114103]，其是对限制性CCSD（RCCSD）的简单修改，其甚至在强相关系统中提供价相关性的定性正确描述。我们导出了CCVB-SD的Λ-方程和相应的非松弛密度矩阵。由此产生的生产级实现应用于寡并苯，在318个轨道中关联多达318个电子。CCVB-SD示出了一个定性的协议与精确的方法短并苯，并达到批量限制oligoacenes的自然轨道占据数，而RCCSD显示nonvariable行为，即使相对较短的并苯。当关联所有价电子而不是仅关联π电子时，发现polyradicaloid特征显著减少。
We demonstrate a block-tensor based implementation of coupled-cluster valence-bond singles and doubles (CCVB-SD) [Small, D. W.; Head-Gordon M. J. Chem. Phys. 2012, 137, 114103] which is a simple modification to restricted CCSD (RCCSD) that provides a qualitatively correct description of valence correlations even in strongly correlated systems. We derive the Λ-equation of CCVB-SD and the corresponding unrelaxed density matrices. The resulting production-level implementation is applied to oligoacenes, correlating up to 318 electrons in 318 orbitals. CCVB-SD shows a qualitative agreement with exact methods for short acenes and reaches the bulk limit of oligoacenes in terms of natural orbital occupation numbers, whereas RCCSD shows nonvariational behavior even for relatively short acenes. A significant reduction in polyradicaloid character is found when correlating all valence electrons instead of only the π-electrons.