Ab-initio calculations of the electronic structure of the alkaline earth hydride anions XH⁻ (X = Mg, Ca, Sr and Ba) toward laser cooling experiment

By the use of the ab initio CASSCF/(MRCI+Q) calculations in the representation ^2s+1Ʌ^(+/−), the adiabatic potential energy curves and the dipole moment curves of the low lying states of the alkaline earth hydride anions (MgH⁻, CaH⁻, SrH⁻ and BaH⁻) have been investigated in their singlet and triplet multiplicities. The spectroscopic parameters T_e, R_e, ω_e, B_e, α_e, the dipole moment μ_e, and the dissociation energy D_e have been also calculated for the bound states of the considered molecules. In addition, a systematic investigation of the transition dipole moment curves for the lowest ¹Σ⁺-¹Π transitions has been done along with the Franck-Condon factor (FCF) corresponding to the X¹Σ⁺-(1)¹Π transition. Using the canonical function approach, a rovibrational study has been performed for finding the rovibrational constants E_v, B_v, D_v and the turning points R_min and R_max for the ground and different excited bound state. Efficient routes may be achieved via the diagonal FCF for the formation of cold and ultracold alkaline earth hydride anions. PACS N^o 31.10. + z, 31.15.A, 31.15.vn, 31.50.Df.