Further comparison with the level-shifting technique revealed that CPCM and level-shifting have different mechanisms for opening the HOMO-LUMO gap. Level-shifting artificially lifts the energies of all virtual orbitals by a constant value regardless of the shape of the MOs, which may mistakenly keep some MOs in the virtual space for many iterations because of the wrong energetic ordering of MOs at the early stage of SCF. This issue is not likely for CPCM, whose selective stabilization or destabilization of specific MOs is based on the MO's local electrostatic environment and is consistent over iterations. Because of this, CPCM performs better than levelshifting in reducing SCF iterations for charge-separated molecules.