A b i n i t i o calculations of the vibration–rotation spectrum of HCS−

Abstract

The three dimensional near equilibrium potential energy and dipole moment surfaces of the electronic ground state of HCS− have been calculated from correlated MCSCF-CI electronic wave functions. These data have been used in perturbation and variational calculations of the bound and electron detachment anharmonic vibration–rotation levels. The electron affinity EA0 is calculated to be 0.41 eV and the equilibrium geometry to be RCH=1.111 Å, RCS=1.687 Å, α=106°. The fundamental vibrational band origins and integrated absorption band intensities are predicted to be 2648 cm−1/1318 cm−2 atm−1 (CH stretch), 1140 cm−1/145 cm−2 atm−1 (bend), and 911 cm−1/50 cm−2 atm−1 (CS stretch) in HCS−. The components of the dipole moment functions are given analytically. The dipole moment in the vibrational ground state of HCS− has been calculated to be 2.122 D. Radiative transition probabilities among low lying vibrational levels have also been evaluated. It is found that the radiative lifetimes vary in a mode-specific way. The theoretical photoelectron spectrum of HCS− and DCS− is reported.