Calculation of P,T-odd effects in TlF including electron correlation

Electron correlation is included for the first time in an ab initio calculation of the interaction of the permanent P,T-odd proton electric dipole moment with the internal electromagnetic field in a molecule. The calculation is performed for the ground state of TlF at the experimental equilibrium, Re=2.0844 A, and at R=2.1 A, using the generalized relativistic effective core potential (GRECP) method, with spin-orbit and correlation effects included by relativistic coupled cluster (RCC). Calculated results with single cluster amplitudes only are in excellent agreement (1% or better) with recent Dirac-Hartree-Fock (DHF) values of the magnetic parameter M; the larger differences occurring between present and DHF volume parameter (X) values, as well as between the two DHF calculations, are explained. Inclusion of electron correlation by GRECP/RCC with single and double excitations has a major effect on the P,T-odd parameters, decreasing M by 12% and X by 24%