Core polarization in coupled-cluster theory induced by a parity and time-reversal violating interaction

TL;DR

This paper investigates how parity and time-reversal violating interactions, especially tensor-pseudotensor electron-nucleus interactions, influence core polarization in coupled-cluster theory, with applications to atomic electric dipole moments.

Contribution

It establishes a detailed correspondence between coupled-cluster and coupled perturbed Hartree-Fock methods for these interactions, including the role of pseudo diagrams.

Findings

Normal CPHF diagrams correspond directly to coupled-cluster diagrams.

Pseudo diagrams in CPHF have a subtle but explicit origin in coupled-cluster theory.

Results are demonstrated through calculations of the electric dipole moment of atomic Hg.

Abstract

The effects of parity and time reversal violating potential, in particular the tensor-pseudotensor electron nucleus interaction are studied. We establish that selected terms representing the interplay of these effects and the residual Coulomb interaction in the coupled-cluster method are equivalent to the coupled perturbed Hartree-Fock. We have shown that the {\em normal} CPHF diagrams have a one-one correspondance in the coupled-cluster theory, but the CPHF pseudo diagrams are present in a subtle way. We have studied the {\em pseudo} diagrams in great detail and have shown explicitly their origin in coupled-cluster theory. This is demonstrated by considering the case of the permanent electric dipole moment of atomic Hg and our results are compared with the results of an earlier calculation.