Ab initioDirac-Hartree-Fock calculations of chemical properties andPT-odd effects in thallium fluoride

Abstract

The theory of $\mathrm{PT}$-odd interactions relevant to existing experimental measurements of the hyperfine structure of TlF is reviewed. We outline a relativistic electronic structure theory based on single-particle four-component Dirac spinors, and implemented using methods borrowed from ab initio quantum chemistry. Numerical calculations are reported of the electronic structure of TlF, some of its chemical properties, and of its $\mathrm{PT}$-odd electronic matrix elements. From these results, and from published experimental data, we derive bounds on the value of the electric dipole moment of the proton, ${d}_{p},$ the tensor coupling constant ${C}_{T},$ and the Schiff moment of the ${}^{205}$Tl nucleus, $Q$, which are now the tightest available for these quantities. General issues regarding the calculation of the electronic structures of molecules containing heavy elements are also addressed.