# Toolbox approach for quasi-relativistic calculation of molecular properties for precision tests of fundamental physics

## TL;DR

This paper introduces a flexible method for calculating relativistic molecular properties using quasi-relativistic wavefunctions, enabling efficient and accurate predictions crucial for fundamental physics tests.

## Contribution

It presents a general scheme for relativistic property calculations with two-component wavefunctions, demonstrated with ZORA, applicable to symmetry-violating properties in molecules.

## Key findings

- ZORA-based results agree well with four-component calculations.
- The method effectively predicts properties for molecules like RaF and TlF.
- RaF's potential in experiments searching for fundamental symmetry violations is confirmed.

## Abstract

A generally applicable approach for the calculation of relativistic one-electron properties with two-component wave functions is presented. The formalism is explicitly evaluated for the example of quasi-relativistic wavefunctions obtained within the zeroth order regular approximation (ZORA). The wide applicability of the scheme is demonstrated for the calculation of parity ($\mathcal{P}$) and time-reversal ($\mathcal{T}$) symmetry violating properties, which are important for searches of physics beyond the standard model of particle physics. The quality of the ZORA results is shown exemplarily for the molecules RaF and TlF by comparison to data from four-component calculations as far as available. Finally, the applicability of RaF in experiments that search for $\mathcal{P,T}$-violation not only in the electronic but also in quark sector is demonstrated.