Potential Energy Function for State X¹∑⁺ of LaH

The present work has derived the potential energy function for the ground state X¹∑⁺ of LaH in Murrell-Sorbie function form. In the first place, the electronic state and it’s reasonable dissociation limits are correctly determined based on Atomic and Molecular Reaction Statics （AMRS）, and then, using the relativistic compact effuctive potential （RCEP） for La, the equilibrium geometry and dissociation energy for LaH have been calculable by the QCISD method. The calculated results for R_e,D_e. B_e α_e ω_e and ω_eχ_e are 2.125Å, 2.623eV, 3.7333 cm^-1, 0.0723 cm^-1, 1461.73 cm^-1 and 21.383cm^-1 respectively, which are in good agreement with experimental or calculated values in reference.