# Ab initio calculations of spectroscopic constants and properties of BeLi +

## TL;DR

This study performs ab initio calculations of spectroscopic constants and molecular properties of the BeLi+ ion using various correlation methods and basis sets, providing accurate results extrapolated to the CBS limit.

## Contribution

It introduces comprehensive ab initio calculations of BeLi+ properties using multiple correlation methods and basis sets, including relativistic effects and CBS extrapolation, for highly accurate results.

## Key findings

- Accurate spectroscopic constants for BeLi+ reported.
- Molecular properties like dipole and quadrupole moments calculated.
- Results extrapolated to the complete basis set limit with error estimates.

## Abstract

We have calculated the ground state spectroscopic constants and the molecular properties, of a molecular ion BeLi + , such as dipole moment, quadrupole moment and dipole polarizability at different levels of correlation: many-body perturbation theory (MP2), coupled cluster method with single and double excitations (CCSD) and CCSD with perturbative triples (CCSD(T)). The correlation consistent polarized valence cc-pVXZ (X=D, T, Q) basis sets and also their augmented counterparts are used together with the non-relativistic and relativistic Hamiltonians. The results are extrapolated to the complete basis set limit (CBS) using exponential-Gaussian function. Thus, accurate and reliable results for BeLi + with the most conservative error estimates on them are reported.