SAC-CI Calculation of a Series of the Lowest 2-Pi-States of HCl+ and HBr+ Ions

The symmetry-adapted-cluster configuration interaction (SAC-CI) method is used for ab initio calculation of electronic structure of HCl+ and HBr+ molecular ions. Potential energy curves (PEC) are obtained for a series of low-lying 2Pi-states starting from the ground state, X-2Pi. The PEC for both HCl+ and HBr+ reveal the corresponding asymptotic behavior beginning from the interatomic distances ~8 a0 for the first three states. These states are well separated, while a complex behavior occurs for the set of 4^2Pi-6^2Pi states with a bound character at short distances.