Ab initio investigation of ground and excited states of ScH molecule

The theoretical study of the electronic structure of Scandium Hydride ScH has been carried out using ab-initio methods. By employing (MRCI-SD/SA-CASSCF) and by using basis sets involving contribution of all electrons of both Scandium and Hydrogen atoms, 18 singlet and 15 triplet low-lying electronic states have been calculated below 28803 cm^-1. Potential energy curves have been plotted and the term values at equilibrium T_e, the vibrational constants ω_e and ω_eχ_e of ScH electronic states have been fitted. In addition, we calculated the permanent electric dipole moments for all these predicted states, the transition dipole moments TDMs within states at a range of internuclear distance around the equilibrium, the vibronic intensities FCF and the radiative lifetime. The calculated spectroscopic constants are in excellent consistency with the available experimental results and with other previous theoretical works. These calculations also predicted many excited states unobserved experimentally. The observed perturbations in D¹Π and C¹Σ⁺ have been investigated in this work.