Theoretical Study of the Rovibronic States of CaO

[Display omitted] ► The spin-rovibronic energy levels of the low-lying electronic states of CaO are investigated. ► The spin-orbit and angular momenta couplings are computed ab initio. ► All these couplings are considered during wave packet time propagation calculations. ► Our results compared well with the experimental data. The spin-rovibronic energy levels of CaO, which result from the couplings of X 1Σ +, a 3 Π, A ′1 Π, b 3Σ +, and A 1Σ + low-lying electronic states, are determined from wave packet time propagations and Prony analysis. The electronic potentials were taken from our previous study [Chem. Phys., 386, 50 (2011)]. The spin-orbit and L ^ coupling functions were determined by CASSCF and MRCI calculations. The effects of spin-orbit coupling on vibrational levels were analyzed in the Ω = 0 +, 0 −, 1 coupling schemes. All spin-vibronic energy levels associated with the a 3 Π, A ′1 Π, b 3Σ +, and A 1Σ + states were determined up to 16 000 cm −1 above the electronic ground-state minimum. The results obtained from the spin-orbit coupling functions are in remarkable agreement with the experimental data extracted using a deperturbation procedure. The final energies calculated for J = 2 and J = 25 are used to compare the experimental observations concerning the X 1Σ +− A 1Σ + transition.