Calculations of the ro-vibrational absorption transition probabilities in triatomic molecules

The variational method is used to determine ro-vibrational wavefunctions for triatomic molecules from ab initio potential energy functions. These wavefunctions are then used, in conjunction with ab initio dipole moment functions, to predict radiative transition probabilities. The method has been applied to electric dipole allowed transitions between ro-vibrational levels of linear HLiH- (up to J = 2) and bent HCS- (up to J = 9) in their electronic ground states. As a result, vibrational bands with P-, Q-, and R-branch intensities are determined. Variances with the usual Honl-London formula for linear molecules are described. The transition energies and absorption probabilities for the fundamental ro-vibrational transitions of the near prolate HCS- ion are predicted.