Abstract
Density-functional theory (DFT) is a prevailing method for predicting the geometry of organic compounds. The ground state geometries have been calculated at the B3LYP/6-31G** and PBE0/6-31G** levels of theories. The excited state geometries have been computed at time dependent DFT (TD-DFT) by using TD-B3LYP/6-31G** and TD-PBE0/6-31G** levels of theories. It has been revealed that the PBE0 functional is better than B3LYP to predict the S-O and S-C bond lengths. Both of the functionals could not reproduce the S-N bond lengths. The B3LYP is good to imitate the C-N and C-O bond lengths. The C-C and C-Cl bond lengths have been impersonated by both the functionals. Moreover, it has also been revealed that the S-N bond length elongated while the C-N bond length shortened from ground to excited state. (C) 2012 Production and hosting by Elsevier B.V. on behalf of King Saud University.