Combining complex conjugation, time-reversal, and spin symmetry projection of coupled cluster wave functions
arXiv:2405.06776
Abstract
Complex conjugation symmetry breaking and restoration generate two non-orthogonal configurations at the Hartree-Fock level that can capture static correlation naturally. In conjunction with broken spin-symmetry coupled cluster theory, the symmetry-projected wave function shows good agreement with full configuration interaction in beryllium hydride insertion, lithium fluoride dissociation, and symmetric stretching of tetrahedral H. By adding spin flip projection, we can also recover time reversal symmetry in the same coupled cluster framework.
accepted by J Phys Chem A