Theoretical investigation of the doublet electronic states of Sr35Cl and Sr79Br molecules

Abstract

The energies of the lowest-lying doublet electronic states of Sr35Cl and Sr79Br have been calculated in the representation 2S+1Λ± (neglecting spin-orbit effects). This is the first time that ab-initio methods (MRCI+Q) based on Complete-Active-Space-Self-Consistent-Field have been employed to determine the first 11 electronic states and the permanent electric dipole moments of these molecules. The transition dipole moments (TDM) between the electronic states have been also calculated.The ground states have 2Σ+ symmetry for both molecules with an internuclear distance Re=2.55Å and Re=2.74Å for Sr35Cl and Sr79Br, respectively. Among the 11 lowest doublet electronic states predicted for each molecule, two have not yet been observed experimentally for Sr35Cl and five for Sr79Br. Potential energy curves (PECs) have been also calculated with equilibrium energies up to 37,000cm−1.Spectroscopic constants have been predicted, including the harmonic vibrational wave number ωe, the relative electronic energy Te referred to the ground state, the rotational constant Be, the equilibrium internuclear distance Re and the transition dipole moments calculated at the internuclear distance Re for the ground state. The calculated energies and the spectroscopic constants are in good agreement with the experimental data with a relative error less than 7% for both molecules.