Parity-mixed coupled-cluster formalism for computing parity-violating amplitudes

We formulate a parity-mixed coupled-cluster (PM-CC) approach for high-precision calculations of parity non-conserving amplitudes in mono-valent atoms. Compared to the conventional formalism which uses parity-proper (PP) one-electron orbitals, PM-CC method is built using (PM) orbitals. The PM orbitals are obtained by solving Dirac-Hartree-Fock equation with electron-nucleus electroweak interaction included (PM-DHF). There several advantages such formulation: (i) reduced role correlations, as most experimentally-accurate date ${}^{133}{\rm Cs}\,$ $6S_{1/2}-7S_{1/2}$ transition, PM-DHF result only 3% away from accurate many-body value, while DHF off 18%; (ii) avoidance directly summing over intermediate states expressions reduces theoretical uncertainties associated highly-excited and core-excited states, (iii) relatively straightforward upgrade existing well-tested large-scale PP-CC codes. reformulate CC terms basis demonstrate that cluster complex numbers opposite real imaginary parts. then use this fact map out strategy through new scheme may be implemented.