The Cr 2 potential energy curve studied with multiconfigurational second-order perturbation theory

Abstract

The potential energy curve of the Cr 2 ground state has been obtained by multiconfigurational second-order perturbation theory. In this study 6–8 singularities appear in the potential curve for bond distances ranging from 1.5 to 2.2 Å. However, these singularities are weak enough to allow the determination of approximate spectroscopic constants. By employing a large atomic natural orbital (ANO) basis set of the size 8s7p6d4f and by including 3s, 3p correlation effects and relativistic corrections, the following values were obtained (experimental data within parentheses): equilibrium bond length r e = 1.71 Å (1.68 Å), harmonic vibrational frequency ω e = 625 cm −1 (481 cm −1) and dissociation energy D 0 = 1.54 eV (1.44±0.06 eV).