A wide adiabatic study has been performed for numerous electronic states of CaLi⁺ molecular ion. The adiabatic potential energy curves and their spectroscopic constants (R_e, D_e, ω_e and T_e) have been calculated using an ab initio approach including a nonempirical pseudo-potential for the Ca and Li cores with the core polarisation potentials operator through full configuration interaction (FCI). Thereafter, the energies of vibrational levels and their spacing for all these states have been reported. In addition, the electric dipole moment curves have been investigated for the (1-19) Σ, (1-12) Π and (1-8) Δ electric states. Moreover it lets us check the extreme transition dipole moments (TDM). These behaviours of TDM are more accustomed to estimate the radiative lifetimes for all vibrational levels in 2¹Σ⁺ and 3¹Σ⁺ states. Also, the bound-bound and the bound-free contribution have been calculated precisely and by employing a Franck–Condon (FC) approximation.

The structural and electronic properties of (SrLi)⁺ molecular ion have been determined by the use of ab initio approaches. Potential energy curves (PECs) with their spectroscopic constants (R_e, D_e, ω_e, T_e, B_e and ω_eχ_e) have been calculated. Also, the vibrational properties and the electric dipole moments, either permanent (PDM) or transition (TDM) ones, have been investigated and analysed. Large Gaussian basis sets, the full valence configuration interaction (FCI) and the formalism of non-empirical pseudo-potential including the two approaches, effective core potential (ECP) and core polarisation potential (CPP), are analysed. Therefore, (SrLi)⁺ is considered as a two effective electrons system. Numerous excited states of symmetries ^1,3Σ⁺, ^1,3Π and ^1,3Δ dissociating below the ionic limit Sr²⁺Li⁻ have been investigated. This study shows interesting behaviours around the avoided crossing related to charge transfer involving important processes in physics and astrophysics such as dynamics, pre-dissociation and inelastic transitions.

An ab-initio calculation was performed to highlight the van der Waals interaction between Ba ^0,+,2+ and helium atoms. The low-lying electronic states for Ba ⁺ He and BaHe systems have been determined with the ECP-CPP and full valence CI theory. However, the core-core interaction for Ba ⁺⁺ He has been calculated by the CCSD(T). As a result, the spectroscopic parameters and the vibrational levels have been derived from Potential Energy Surface (PES) and compared with available theoretical and experimental data. Then, the permanent dipole moments for the ground and the excited states are determined. These results show an important shape in PES and allow checking the strong repulsive interactions between Rydberg electrons and the He atom. Furthermore, structures and stabilities of the Ba ⁺⁺ He _n mixed-clusters have been investigated by exploring the PES based on the BHMC algorithm. The most stable icosahedral structure was detected at n = 12 and the snowball shell was completed at n = 20.