Caspt2 Study On Low-Lying States Of Hmgo And Homg

The HMgO and magnesium monohydroxide (HOMg) have been reinvestigated using the complete active space self-consistent field (CASSCF) and multiconfiguration second-order perturbation theory (CASPT2) methods with the contracted atomic natural orbital (ANO) basis sets. The geometries of all stationary points along the potential energy surfaces (PESs) were optimized at the CASSCF/ANO levels. The ground and the first excited states of HMgO are predicted to be X-2 Sigma(+) and A(2)Pi states, respectively. It was predicted that the ground state of HOMg is X-2 Sigma(+) state. The A(2)Pi state of HOMg has unique imaginary frequency. A bent local minimum M1 was found for the first time along the 1(2)A'' PES and the A(2)Pi state of HOMg should be the transition state of the isomerization reactions for M1 <-> M1. The CASPT2/ANO potential energy curves of isomerization reactions were calculated as a function of HMgO bond angle. (C) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012