Assessment of XC functionals for the study of organic molecules with superhalogen substitution. A systematic comparison between DFT and CCSD(T)

摘要

A systematic density functional theory study, including 17 exchange-correlation functionals, was performed on 22 composite structures consisting of organic molecules, e.g., ethylene, ethane, and benzene, and superhalogen substitutions arising from MgX3(-) and Mg2X5(-) (X = F, Cl). Range-separated hybrid functionals omega B97M-V, omega B97X-D3(BJ), omega B97XD, omega B97X, and CAM-B3LYP, as well as double-hybrid functionals B2PLYP and DSD-PBEP86-D3(BJ), are verified to provide reliable results with accuracy approaching that at the coupled-cluster single double triple CCSD(T) level. The basis set effect of density functional theory calculation is usually moderate, and triple-xi quality, e.g., Def2-TZVP, is enough in most cases. In addition, the average values from HF and MP2 method, indicated as (MP2 + HF)/2, are also quite close to those of CCSD(T). Published under an exclusive license by AIP Publishing.