Ab initio calculations of the xi molecules (X = Li, Na, K, Rb) with the ionicity and laser cooling analysis

For the alkali iodide molecules LiI, NaI, KI, and RbI, ab initio CASSCF/(MRCI+Q) calculations have been employed to investigate the adiabatic potential energy curves and the static dipole moment curves of the low-lying singlet and triplet electronic states in the representation^2S+1⋀^(+/−). The spectroscopic constants T_e, R_e, ω_e, B_e, α_e, the dipole moment μ_e, and the dissociation energies D_e have been computed for the bound states. Additionally, the percentage ionic character f_ionic around the equilibrium position of the ground state and the (2)¹∑⁺ state has been estimated. Using the canonical function approach, these calculations have been followed by a rovibrational calculation from which the rovibrational constants E_v, B_v, D_v, and the abscissas of the turning points R_min and R_max for the investigated bound states are calculated.