Ab initio potential curves for the X $^2 \Sigma_{u}^+$ and B $^2 \Sigma_{g}^+$ states of Be$_{2}^+$: Existence of a double minimum

TL;DR

This paper presents high-level ab initio calculations of the Be₂⁺ dimer's electronic states, revealing a double minimum in the B state and providing spectroscopic data consistent with recent experiments.

Contribution

The study provides the first detailed ab initio potential energy curves for both states of Be₂⁺, including a double minimum in the B state, with comprehensive spectroscopic constants and vibrational data.

Findings

Discovery of a double minimum in the B state potential

Good agreement with recent experimental spectroscopic data

Calculation of vibrational levels, transition moments, and lifetimes

Abstract

We report ab initio calculations of the X $^2 \Sigma_{u}^+ $ and B $^2 \Sigma_{g}^+$ states of the Be$_{2}^+$ dimer. Full valence configuration interaction calculations were performed using the aug-cc-pVnZ basis sets and the results were extrapolated to the CBS limit. Core-core, core-valence effects are included at the CCSDT/MTsmall level of theory. Two local minima, separated by a large barrier, are found in the expected repulsive B $^2 \Sigma_{g}^+$ state. Spectroscopic constants have been calculated and good agreement is found with the recent measurements of Merritt et al. Bound vibrational levels, transition moments and lifetimes have also been calculated.