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A New Benchmark Set for Excitation Energy of Charge Transfer States: Systematic Investigation of Coupled Cluster Type Methods.
Journal of Chemical Theory and Computation ( IF 5.5 ) Pub Date : 2020-06-05 , DOI: 10.1021/acs.jctc.0c00154
Balázs Kozma 1 , Attila Tajti 1 , Baptiste Demoulin 2 , Róbert Izsák 2 , Marcel Nooijen 3 , Péter G Szalay 1
Affiliation  

The numerous existing publications on benchmarking quantum chemistry methods for excited states rarely include Charge Transfer (CT) states, although many interesting phenomena in, e.g., biochemistry and material physics involve the transfer of electrons between fragments of the system. Therefore, it is timely to test the accuracy of quantum chemical methods for CT states, as well. In this study we first propose a new benchmark set consisting of dimers having low-energy CT states. On this set, the vertical excitation energy has been calculated with Coupled Cluster methods including triple excitations (CC3, CCSDT-3, CCSD(T)(a)*), as well as with methods including full or approximate doubles (CCSD, STEOM-CCSD, CC2, ADC(2), EOM-CCSD(2)). The results show that the popular CC2 and ADC(2) methods are much less accurate for CT states than for valence states. On the other hand, EOM-CCSD seems to have similar systematic overestimation of the excitation energies for both types of states. Among the triples methods the novel EOM-CCSD(T)(a)* method including noniterative triple excitations is found to stand out with its consistently good performance for all types of states, delivering essentially EOM-CCSDT quality results.

中文翻译:

电荷转移态激发能的新基准集:耦合簇类型方法的系统研究。

现有的许多关于激发态的量子化学方法基准测试的出版物很少包括电荷转移(CT)态,尽管例如生物化学和材料物理学中的许多有趣现象都涉及电子在系统碎片之间的转移。因此,也应及时测试量子化学方法在CT状态下的准确性。在这项研究中,我们首先提出一个新的基准集,该基准集由具有低能CT状态的二聚体组成。在此集合上,已通过耦合簇方法(包括三重激发(CC3,CCSDT-3,CCSD(T)(a)*))以及包括全双倍或近似双倍的方法(CCSD,STEOM- CCSD,CC2,ADC(2),EOM-CCSD(2))。结果表明,流行的CC2和ADC(2)方法对于CT状态的准确度要比对价态的准确度低得多。另一方面,对于两种状态,EOM-CCSD似乎都对激发能进行了类似的系统高估。在三重方法中,发现包含非迭代三重激发的新颖EOM-CCSD(T)(a)*方法在所有类型的状态中始终如一的良好性能脱颖而出,基本上提供了EOM-CCSDT质量结果。
更新日期:2020-07-14
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