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

Abstract

The effects of a 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 (CPHF). We have shown that the normal CPHF diagrams have a one-to-one correspondence in the coupled-cluster theory, but the CPHF pseudo diagrams are present in a subtle way. We have studied the pseudo diagrams in great detail and have shown explicitly their origin in the 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.