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

Abstract

An adiabatic study of 1-34 (1,3)Σ(+) electronic states of barium hydride ion (BaH(+)) is presented for all states dissociating below the ionic limit Ba(2+)H(-). The 1-20 (1,3)Π and 1-12 (1,3)Δ states have been also investigated. In our approach, the valence electrons of the Ba(2+) 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 Re, De, Te, ωe, ωexe, and Be 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 (1)Σ(+) states exhibit ionic charge transfer avoided crossings series which could lead to neutralization or even H(-) formation in collisions of H(+) with Ba.

Ab initio calculation of the electronic structure of the strontium hydride ion (SrH+)

“…The assignments of the low‐lying higher states have been confirmed experimentally. Among the various ab initio calculation for the first state X 1 Σ + of these ionic systems, the spectroscopic constants of BaH + calculated by Mejrissi et al meet the best agreement with experimental data.…”

“…The computed PDM value of the ground state for these cations provides estimation for the associated Stark shifts . In addition the good quality calculations of electric dipole properties (PDM) on molecules such as CaH + , BaH + , and MgH + are very interesting and constitute the first step to illustrate the repartition of charges in the adiabatic states . Consequently, we have investigated the PDM and TDM functions of SrH + for all states bellow the ionic limit mainly to better know the ionic character of the 1 Σ + states at the vicinity of the avoided crossing and in the other symmetries also.…”

“…We note also that the crossings seen in the dipole moment curves coincide with the crossings positions previously seen in the PECs. The PDM can, thus, give interesting information about the physical nature of the states as for the molecules CaH + , BaH + , and MgH + . Let us recall that the avoided crossing may have significant role for the excitation or charge transfer efficiency.…”

“…Interestingly, the 1 Σ + states present an important series of avoided crossing. Their highly potential energy is strongly imprinted by the ionic state Sr 2+ H − like for BaH + , CaH + and MgH + systems . The multiplicity of crossings leads to unusual potential shapes with various wells which may trap vibrational levels in various R ranges.…”

“…Motivated by the numerous experimental works on alkaline earth hydrides cation, numerous theoretical investigations have been performed for YH + systems . Both adiabatic potential energy and dipole moments of these diatomic hydride cations have been investigated by various numerical methods.…”