Adiabatic ab Initio Study of the BaH⁺ Ion Including High Energy Excited States

An adiabatic study of 1–34 ^1,3Σ⁺ electronic states of barium hydride ion (BaH⁺) is presented for all states dissociating below the ionic limit Ba²⁺H^–. The 1–20 ^1,3Π and 1–12 ^1,3Δ states have been also investigated. In our approach, the valence electrons of the Ba²⁺ ion described by an effective core potential (ECP) and core polarization potential (CPP) with l-dependent cutoff functions have been used. The ionic molecule BaH⁺ has been treated as a two-electron system, and the full valence configuration interaction (CI) is easily achieved. The spectroscopic constants R_e, D_e, T_e, ω_e, ω_ex_e, and B_e are derived. In addition, vibrational level spacing and permanent and transition dipole moments are determined and analyzed. Unusual potential shapes are found and also accidental quasidegeneracy in the vibrational spacing progression for various excited states. The ¹Σ⁺ states exhibit ionic charge transfer avoided crossings series which could lead to neutralization or even H^– formation in collisions of H⁺ with Ba.