The spectrum of antimony hydride: An ab initio configuration interaction study employing a relativistic effective core potential

Abstract

An ab initio configuration interaction (CI) study including the spin–orbit interaction is carried out for numerous valence and Rydberg states of the SbH radical by employing a relativistic effective core potential for the antimony atom. The computed spectroscopic constants are in good agreement with available experimental data, with a tendency toward a slight overestimation of bond lengths (by 0.01–0.03 Å) and Te values (by 370–550 cm−1) for the lowest singlet states. Measured excitation energies and spin–orbit splittings for the A 3Π multiplet are also accurately reproduced in the present calculations and the Ω=0−, 1, and 2 components of this state are shown to be strongly predissociated due to spin–orbit interaction with the corresponding components of the repulsive Σ−5 state. The most stable representative of the A 3Π multiplet, A40+, is found to possess a very unusual potential curve with a double minimum and a fairly low barrier to dissociation. Based on a vibrational analysis of this state it is concluded that the earlier observed B0+ and C0+ electronic states should be attributed to the v=0 and 2 vibrational levels of the A40+ state, while the state experimentally assigned as A 3Π0+ corresponds to the A40+, v=1 level. Dipole moments μ(v=0) for the …σ2π2 X3Σ−, a 1Δ and b 1Σ+ states are computed to have small (e.g., −0.238 D for X1 3Σ0+−) and nearly equal negative values (Sb+H− polarity). The dipole transition moments and the corresponding radiative lifetimes for a number of low-energy electronic transitions have also been computed. Many other bound states and avoided crossings are indicated in the calculations which may be of relevance in future experimental studies of this system.