Electronic Structure with Rovibrational Calculations of the Magnesium Monohalides MgX and Their Cations MgX⁺ (X = Cl, Br, and I)

Alkaline-earth monohalides are popular compounds that are used in various applications. Little is known, however, in terms of electronic structure, about their cations and their low-lying electronic states. We present in this work electronic structure ab-initio calculations based on multireference configuration interaction plus Davidson correction of three magnesium monohalides and their cations (MgCl, MgBr, MgI, MgCl⁺, MgBr⁺, and MgI⁺). We determine the spectroscopic constants T_e, R_e, ω_e, B_e, and α_e and the dissociation energies D_e for their bound states. Additionally, we investigate their vibrational properties by calculating the vibrational eigenvalue E_v, the rotational constant B_v, and the centrifugal distortion constant D_v. We additionally study the electric charge distribution of several states by determining their permanent dipole moment and transition dipole moment curves. Finally, we calculate the Franck–Condon factors and the radiative lifetimes as precursors for laser cooling experiments.