Theoretical electronic structure of the NaBe molecule

•Investigation of 24 electronic states of the BeNa molecule.•A ro-vibrational calculation with Einstein coefficients and dipole moments.•Franck-Condon calculation and discussion for laser cooling experiments.

A theoretical study of the low-lying electronic states of NaBe molecule has been investigated via the CASSCF/MRCI (single and double excitations with Davidson correcrtion) method using the correlation-consistent basis set pwCV5Z. Two sets of frozen core orbitals (FCOs) are adopted to estimate the correlation effect of the inner-shell electrons on the molecular properties. The spectroscopic constants are determined for the electronic bound states. The Einstein coefficients, the spontaneous radiative lifetime and the emission oscillator strength have been calculated for the lowest electronic transitions. The ro-vibrational parameters have been obtained for different electronic states by using the canonical functions approach. Twenty-two electronic states are studied theoretically here for the first time. Our evaluation of the potential energy curves leads to significantly off-diagonal Franck-Condon factors for the transitions X2Σ+-(2)2Σ+ and X2Σ+-(1)2Π which shows that the highly diagonal FCFs criterion for laser cooling is not verified for the NaBe molecule.

Graphical abstractFor the molecule NaBe the potential energy curves of 24 electronic states in the representation Λ(+/−) have been calculated along the spectroscopic constants ωe, Re, Te, the Einstein coefficients, Franck-Condon factor, the permanent and transition dipole moment, and the rovibrational parameters Ev, Bv, Rmin and Rmax.Download high-res image (56KB)Download full-size image