Approximate spin-projected broken symmetry energies from optimized orbitals that are unrestricted in active pairs

► We derive and implement an orbital optimized approach to calculate the approximate spin-projected broken symmetry energy. ► Potential energy curves for homolytic dissociation of H2 are smooth and first derivative continuous. ► Static correlation energy recovered at extended H-H and N-N distances is comparable to the Yamaguchi APBS method.