Electronic states and potential energy curves of ZrH + and NbH +

Abstract

State-averaged complete active space MCSCF (CASSCF) followed by second-order configuration interaction (SOCI) calculations are carried out on several low-lying electronic states of ZrH + and NbH +. The ground state of ZrH + is found to be a 3Δ state ( r e = 1.825 A ̊ , ω e = 1752 cm −1) with a very low-lying excited state of 3Φ symmetry ( r e = 1.841 A ̊ , ω e = 1714 cm −1). The NbH + ion has 4Δ state as the ground state ( r e = 1.746 A ̊ , ω e = 1841 cm −1) with a nearly degenerate state of the 4Π symmetry ( r e = 1.768 A ̊ , ω e = 1826 cm −1). The dissociation energies D 0 (ZrH +) D 0 (NbH +) are calculated to be 56.8 and 54 kcal/mol, compared to experimental values of 54 ± 3 and 53 ± 3 for ZrH + and NbH +, respectively. The nature of low-lying states is analyzed.