Theoretical study on low-lying states of HAlO~+ and HOAl ~+ cations

摘要

Some low-lying states of HAlO~+ and HOAl~+ cations have been studied 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 were optimized at the CASSCF/ANO and CASPT2/ANO levels. The ground and the first excited states of HAlO~+ are predicted to be X~2Π and A~2Σ ~+ states, respectively. It was predicted that the ground state of HOAl~+ is X~2Σ~+ state. The A ~2Π state of HOAl~+ has unique imaginary frequency. A bent local minimum M1 was found along the 1~2A″ potential energy surface, and the A~2Π state of HOAl~+ 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 HAlO bond angle.