Electron correlation and nuclear charge dependence of parity-violating properties in open-shell diatomic molecules

TL;DR

This paper investigates how nuclear charge influences parity-violating effects in open-shell diatomic molecules, using relativistic and correlation calculations to understand their scaling and improve prediction accuracy.

Contribution

It demonstrates the ZORA framework's effectiveness in modeling parity violation and highlights the importance of electron correlation for precise predictions in radium fluoride.

Findings

W_a scales with Z^k and relativistic enhancement factors.

Electron correlation significantly affects parity-violating predictions.

Systematically improvable correlation methods are necessary for high accuracy.

Abstract

The scaling of nuclear spin-dependent parity violating effects with increasing nuclear charge $Z$ is discussed in two series of isovalent open-shell diatomic molecules. The parameter $W_\mathrm{a}$ characterising the strength of parity violation in diatomic molecules is calculated in the framework of the zeroth-order regular approximation (ZORA) and found to be in good agreement with the $R(Z) Z^k$ scaling law derived for atoms in which $R(Z)$ represents a relativistic enhancement factor. The influence of electron correlation is studied on the molecular level, with spin-polarisation effects being conveniently accounted for by a previously established approximate relation between the hyperfine coupling tensor and $W_\mathrm{a}$. For high accuracy predictions of parity violating effects in radium fluoride the necessity for systematically improvable correlation calculations is emphasised.