Symmetry-adapted-cluster configuration interaction study of the doublet states of HCl$^+$: Potential energy curves, dipole moments, and transition dipole moments

The electronic structure of the HCl<SUP>+</SUP> molecular ion has been calculated using the general-R symmetry-adapted-cluster configuration interaction (SAC-CI) method. The authors present the potential energy curves, dipole moments, and transition dipole moments for a series of doublet states. The data are compared with the previous CASSCF and MCSCF calculations. The SAC-CI results reproduce quite well the data available in literature and extend the knowledge on the HCl<SUP>+</SUP> electronic structure for several higher states. The calculated R-dependent behavior of both dipole moments and transition dipole moments for a series of bound and unbound states reveals an intricate dissociation process at intermediate distances (R>R<SUB>e</SUB>). The pronounced maxima in transition dipole moment (TDM) describing transitions into high electronic states (X <SUP>2</SUP>Pi-->3 <SUP>2</SUP>Pi, X <SUP>2</SUP>Pi-->3 <SUP>2</SUP>Sigma, 2 <SUP>2</SUP>Pi-->3 <SUP>2</SUP>Pi, 3 <SUP>2</SUP>Pi-->4 <SUP>2</SUP>Pi) occur at different interatomic separations. Such TDM features are promising for selection of excitation pathways and, consequently, for an optimal control of the dissociation products.