Theoretical investigation of the low-lying electronic states of the alkaline hydride BeH2+ ion: Potential energy curves, spectroscopic constants, vibrational levels, and transition dipole functions

Abstract

The structure and spectroscopic properties of the alkaline hydride BeH 2+ ion have been investi gated using an ab initio approach based on nonempirical pseudopotentials and parameterized l dependent polarization potentials. The adiabatic potential energy curves and their spectroscopic constants for the ground and seventeen excited electronic states, dissociating into Be + (2s, 2p, 3s, 3p, 3d, 4s, 4p, and 4d) + H + and Be 2+ + H(1s and n = 2), of 2 Σ + , 2 Π, and 2 Δ symmetries have been determined. As no experimental data are available, our results are discussed and compared with the few existing theoretical calculations. A very good agreement has been found with the previous theoretical data for the ground state; however many poten tial energy curves for the higher excited states are presented here, for the first time. Numerous avoided cross ings between electronic states for 2 Σ + and 2 Π symmetries have been localized and analyzed. Their existence is related to the interaction between the electronic states and to the charge transfer process between the two ionic systems Be 2+ H and Be + H + . In addition, we have calculated the vibrational energy level spacings of the bound electronic states. Furthermore, the adiabatic transition dipole functions from the X 2 Σ + and 2 2 Σ + states to the higher excited states of 2 Σ + and 2 Π symmetries have been evaluated and compared with the available theoretical work. This study represents the necessary initial step towards the investigation of the charge trans fer processes in collision between Be + -H + and Be 2+ -H. Fig. 4. Transition dipole functions from X 2 Σ + to the higher 2 Σ + excited states (solid line) compared with Ornellas et al. [9] for X 2 Σ + -2 2 Σ + and X 2 Σ + -3 2 Σ + transitions (dashed line) of the alkaline hydride BeH 2+ ion.

Accurate Ab Initio Investigation of Electronic and Radiative Properties, and Cross Sections for Charged Diatomic Systems FrLi+ and FrNa+

“…Additionally, for higher electronic states, we observed avoided crossings between the adiabatic potential energy curves of 2 Σ + symmetry at large distances. Similar behavior has been documented in previous investigations involving charged systems, including LiK +9 , NaK +12 , LiRb +11 , BeX 2+ (XH, Li, Na, K, Rb, and Cs), − BeH +30 , BeLi +31 and SrH +32 . In the case of FrLi + , we found avoided crossings between the electronic states 4 2 Σ + /5 2 Σ + , 5 2 Σ + /6 2 Σ + and 8 2 Σ + /9 2 Σ + at distances of 11.20 au, 9.15, 19.50, and 42.27 au, and 19.17 au, respectively.…”

“…The current work builds upon our previous theoretical investigations − ,,− concerning the structural and spectroscopic properties of neutral and charged diatomic molecules composed of alkali and alkaline earth atoms. In this article, we extend our calculations to study the electronic properties and elastic collisions of the charged diatomic systems FrLi + and FrNa + using the same method.…”

Exploration of interlacing and avoided crossings in a manifold of potential energy curves by a Unitary Group Adapted State Specific Multi-Reference Perturbation Theory (UGA-SSMRPT)

“…BeH 2+ is a short-lived, metastable dication which has been studied both theoretically and experimentally in the last decade 60 . The ground 2 Σ + state shows a moderately strong avoided crossing with the 1st excited 2 Σ + state at short distance, resulting in rapid disso-ciation to the repulsive Be + ( 2 S) and H + fragments.…”