Relativistic coupled-cluster calculations of time-reversal symmetry-violating sensitivity parameters as analytic energy derivatives

Quantum-mechanical computations for effective electric fields, the time-reversal symmetry-violating sensitivity parameters pertinent to the search for the electron’s electric dipole moment (eEDM), play important roles in the interpretation of experimental measurements and in the selection of candidate molecules. We have developed an analytic-gradient-based method for relativistic exact two-component coupled-cluster calculations of effective electric fields to enhance the efficiency and robustness of the computations. The accuracy of the computed parameters is studied by comparing the results with the four-component calculations and by analyzing the convergence of the results with respect to the level of the treatments for electron-correlation effects. We further report the calculations of effective electric fields for a variety of molecular species and discuss the effects of the electronic-structure properties of these molecules on the computed effective electric fields.