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

Abstract

This paper presents an extensive ab initio investigation of the electronic properties and elastic collisions of charged diatomic systems FrLi + and FrNa + . We employ an accurate ab initio approach using nonempirical pseudopotentials for Li + , Na + , and Fr + cores. We calculate the potential energy curves of the ground state and low-lying excited states of 2 Σ + , 2 Π, and 2 Δ symmetries, identifying and interpreting avoided crossings between higher 2 Σ + and 2 Π states. The spectroscopic parameters, transition dipole moments, and vibrational energies associated with 1−3 2 Σ + states are calculated, along with the radiative lifetimes of the vibrational states trapped in the 2 2 Σ + state. Using accurate potential energy data, we evaluate partial and total cross sections across a wide range of energies. At low energies (<1 mK), the elastic cross section follows the Wigner law threshold comportment, while at high energies, it scales as E −1/3 . To the best of our knowledge, no theoretical or experimental data have been collected on these charged diatomic systems until now. Hence, we proceeded to analyze our findings by comparing them with data acquired from comparable systems. The information pertaining to electronic structures, spectroscopic parameters, transition properties, and collision data provided in this work is expected to serve as a valuable guideline for future theoretical and experimental research on each considered system.