Ab initio relativistic treatment of the intercombination $a^3\Pi-X^1\Sigma^+$ Cameron system of the CO molecule

TL;DR

This study computationally investigates the relativistic effects on the intercombination Cameron system of CO using advanced quantum chemistry methods, providing new transition probabilities, lifetimes, and exploring fundamental constant variations.

Contribution

It introduces a relativistic ab initio approach to accurately model the Cameron system of CO, including transition probabilities and effects of fine structure constant variation.

Findings

Calculated weak transition probabilities and lifetimes of the $a^3\Pi$ state.

Compared theoretical results with experimental data, showing good agreement.

Evaluated the impact of fine structure constant variation on transition strengths.

Abstract

The intercombination $a^3\Pi - X^1\Sigma^+$ Cameron system of carbon monoxide has been computationally studied in the framework of multi-reference Fock space coupled cluster method with the use of generalized relativistic pseudopotential model for the effective introducing the relativity in all-electron correlation treatment. The extremely weak $a^3\Pi_{\Omega=0^+,1} - X^1\Sigma^+$ transition probabilities and radiative lifetimes of the metastable $a^3\Pi$ state were calculated and compared with their previous theoretical and experimental counterparts. The impact of a presumable variation of the fine structure constant $\alpha=e^2/\hbar c$ on transition strength of the Cameron system has been numerically evaluated as well.