Premium
Density functional and multiconfigurational ab initio study of the ground and excited states of Os 2
Author(s) -
Kim Joonghan,
Kim Jeongho
Publication year - 2014
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.24715
Subject(s) - ground state , ab initio , density functional theory , perturbation theory (quantum mechanics) , excited state , bond dissociation energy , multireference configuration interaction , chemistry , atomic physics , configuration interaction , bond length , dissociation (chemistry) , complete active space , computational chemistry , physics , quantum mechanics , basis set , molecule , organic chemistry
Multiconfigurational ab initio methods predict that the 5 Π u state as the ground state instead of the 7 Δ u state. Although multiconfigurational perturbation theory correctly predicts the ground state, they overestimate the bond dissociation energy (BDE). Only multireference configuration interaction method can reasonably calculate the BDE. The spin‐orbit effect on the spectroscopic constants is not significant. The results calculated by density functional theory (DFT) vary significantly depending on the selection of a DFT functional. No DFT functional gives the same energy ordering as calculated by the second‐order multiconfigurational perturbation theory (CASPT2). The old generalized gradient approximations functionals are well suited for predicting the ground state and calculating the bond length and the vibrational frequency of Os 2 . According to the CASPT2 calculation, the ground state of Os 2 has a quadruple bond. © 2014 Wiley Periodicals, Inc.