Nuclear structure and Breit interaction effects in relativistic molecular electronic structure calculations

Abstract

We examine the effects of nuclear structure and the self-consistent treatment of the Breit interaction on the calculation of properties associated with PT-odd interactions in TlF. We also demonstrate that 99.9999% of the Breit energy in TlF is recovered from the one-centre contributions to the interaction energy in the self-consistent field approximation. The formulation of our electronic structure code, BERTHA, facilitates the evaluation of all one-centre effects using efficient methods borrowed from relativistic atomic physics at negligible computational cost. A further analysis of this behaviour is provided for the homonuclear mean-field system, At, in the Dirac–Hartree–Fock–Breit approximation. For closed-shell systems, a formal analysis of the origin of this behaviour suggests that this computational economy may be of general applicability in relativistic molecular electronic structure theory.