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State-Averaged Pair Natural Orbitals for Excited States: A Route toward Efficient Equation of Motion Coupled-Cluster
Journal of Chemical Theory and Computation ( IF 5.7 ) Pub Date : 2018-09-25 00:00:00 , DOI: 10.1021/acs.jctc.8b00171
Chong Peng 1 , Marjory C. Clement 1 , Edward F. Valeev 1
Affiliation  

A reduced-complexity variant of equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) method is formulated in terms of state-averaged excited-state pair natural orbitals (PNO) designed to describe manifolds of excited states. State-averaged excited-state PNOs for the target manifold are determined by averaging CIS(D) pair densities over the model manifold. The performance of the PNO-EOM-CCSD approach has been tested with the help of a distributed-memory parallel canonical EOM-CCSD implementation within the Massively Parallel Quantum Chemistry program that allows treatment of systems with 50+ atoms using realistic basis sets with 1000+ functions. The use of state-averaged PNOs offers several potential advantages relative to the recently proposed state-specific PNOs: our approach is robust with respect to root flipping and state degeneracies, it is more economical when computing large manifolds of states, and it simplifies evaluation of transition-specific observables such as dipole moments. With the PNO truncation threshold of 10–7, the errors in excitation energies are on average below 0.02 eV for the first six singlet states of 28 organic molecules included in the standard test set of Thiel and co-workers (J. Chem. Phys.2008, 128, 134110) with 50–70 state-averaged PNOs per pair.

中文翻译:

激发态的平均状态对自然轨道:通向运动耦合簇有效方程的一条途径

运动方程耦合簇单双打法(EOM-CCSD)方法的降低复杂性变体是根据描述激发态流形的状态平均激发态对自然轨道(PNO)制定的。目标歧管的状态平均激发态PNO通过对模型歧管上的CIS(D)对密度进行平均来确定。PNO-EOM-CCSD方法的性能已经在大规模并行量子化学程序中借助分布式内存并行规范EOM-CCSD实现的测试进行了测试,该程序允许使用1000+以上的实际基数来处理50+个原子的系统功能。与最近提出的特定于状态的PNO相比,使用状态平均的PNO具有几个潜在的优势:我们的方法在根翻转和状态简并性方面很健壮,在计算大量状态集时更经济,并且简化了对特定于过渡的可观观测值(如偶极矩)的评估。PNO截断阈值为10-7,在激发能的误差平均小于0.02电子伏特的前六个单元28个的有机分子包括在标准测试集泰尔和同事(的状态J.化学物理。2008,128,134110)与每对50-70个状态平均的PNO。
更新日期:2018-09-25
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