To test the various core-hole-constraining approaches that were introduced above, we implemented fractional occupancy methods in a locally-modified copy of Q-Chem. (These methods will be released in Q-Chem v. 6.1.) Several algorithms are available to optimize a non-Aufbau determinant that contains a fractional core hole, but the calculations presented here use either the MOM algorithm 62 or the "initial MOM" (IMOM) algorithm. These differ only in whether overlaps are computed with respect to the previous SCF cycle's occupied MOs (in the MOM procedure) or the initial set of MOs at the first SCF cycle (in IMOM).