title: A coupled cluster approach with excitations up to six orbital pairs: the formulation and test applications for bond breaking processes.
abstract: The formalism of the coupled cluster (CC) method with excitations up to six orbital pairs (CC6P) and its illustrative applications are presented. By definition, CC6P includes connected excitations from full singles, doubles, triples, and partial quadruples, pentuples, and hextuples. CC6P and its approximate variants (CC6P-4, CC6P-5, and CC6P-6a) have the similar computational cost as the CC singles, doubles, and triples (CCSDT). They have been applied to investigate the potential energy surfaces for bond dissociation processes in four small molecules (F(2), H(2)O, N(2), and F(2)(+)). In comparison with full configuration interaction results, CC6P and its approximate variants are demonstrated to provide very accurate descriptions for the single-bond breaking process in F(2). While for multi-bond breaking processes, these methods provide considerable improvement over CCSDT.
authors.affiliation: School of Chemistry and Chemical Engineering, Key Laboratory of Mesoscopic Chemistry of Ministry of Education, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093, People's Republic of China.
authors.forename: Enhua
authors.initials: E
authors.lastname: Xu
authors.forename: Zhuangfei
authors.initials: Z
authors.lastname: Kou
authors.forename: Shuhua
authors.initials: S
authors.lastname: Li