Calibration (test) calculations of adiabatic curves of potential energy, permanent electric dipole moments, and dipole moments of spin-allowed electronic transitions were performed for the ground and several low-lying excited singlet states of an isolated calcium monoxide molecule. Based on a systematic comparison of ab initio results obtained in this study with each other, as well as with alternative theoretical and experimental data available in the literature, it was concluded that the most adequate results for calculating the electronic structure of CaO were obtained only within the framework of the MR-AQCC method and then only within a relatively narrow range of internuclear distances.
Pazyuk et al. (2026) studied this question.