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We study theoretically the structure and spectroscopic properties of the alkali alkaline-earth (LiBe) + ion. The potential energy curves and their spectroscopic parameters, permanent and transition dipole moments are determined with a quantum chemistry approach. The (LiBe) + ion is modelled as two valence electron system moving in the field of Be 2+ and Li + cores, which are described by pseudopotentials. In addition, effective core-polarization potentials are included to correct the energy. The molecular calculations are performed using a standard quantum chemistry approach based on the pseudopotential model, Gaussian basis sets, effective core polarization potentials, and full configuration interaction (CI) calculations. The precision of our spectroscopic parameters are discussed by comparison with currently available theoretical results. A rather good agreement is observed for the ground and first excited states. The permanent dipole moments reveal many abrupt changes, which are localized at particular distances corresponding to the positions of the avoided crossings.

In this theoretical work, we calculate potential energy curves, spectroscopic parameters and transition dipole moments of molecular ions BeX + (X=Na, K, Rb) composed of alkaline ion Be and alkali atom X with a quantum chemistry approach based on the pseudopotential model, Gaussian basis sets, effective core polarization potentials, and full configuration interaction (CI). We study in detail collisions of the alkaline ion and alkali atom in quantum regime. Besides, we study the possibility of the formation of molecular ions from the ion-atom colliding systems by stimulated Raman adiabatic process and discuss the parameters regime under which the population transfer is feasible. Our results are important for ion-atom cold collisions and experimental realization of cold molecular ion formation.

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The electronic structure and the spectroscopic properties for low-lying electronic states of the LiRb þ molecular ion, dissociating into Li (2s, 2p, 3s, 3p, 3d, 4s, and 4p) þ Rb þ and Li þ þ Rb (5s, 5p, 4d, 6s, 6p, 5d, and 7s), have been investigated using an ab initio approach based on non-empirical pse-udo potentials for the Li and Rb cores and parametrized l-dependent polarization potential. We have determined the adiabatic potential energy curves and their spectroscopic constants for many electronic states of 2 R þ , 2 P, and 2 D symmetries. A satisfying agreement, for the [a] C.

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Based on the ab-initio approach and using the non-empirical pseudo-potential formalism for Be2+, Na+, K+ and Rb+ cores, large Gaussian basis sets and full valence configuration interaction (FCI), alkali-metal atom and the Beryllium ionic pairs are treated as effective two-electron systems. The potential energy curves and their spectroscopic constants for the low-lying excited states of different1,3Σ+, 1,3Πand 1,3Δ symmetries of these molecular ions have been performed. In addition to the vibrational properties, permanent and transition dipole moments functions have been also calculated and analyzed. The lifetimes of the vibrational states of the ground state are calculated taking into account the decay rates of the vibrational states in terms of spontaneous emission, and stimulated emission induced by black body radiation. The radiative lifetimes of the vibrational levels of the first A1Σ+ and second C1Σ+excited states are calculated using both ‘Franck-Condon’ and ‘Sum rule’ approximations. In all studied alkali-metal Beryllium molecular ions the ground states X1∑+ have much longer lifetimes than any excited states with an order of second, while an order of nanosecond is found for the first and second excited states, A1Σ+ and C1Σ+.

The BeCs+ system represents a possible future candidate for the realization of samples of cold or ultra-cold molecular ion species that it has been not yet investigated experimentally nor theoretically....