A comparison to EPs produced by the CP 3 with only charges (CP 3 -q) reveals that the isotropic polarizabilities yield a substantial improvement in all cases, reducing the RMSD by roughly 10 kJ/mol on average. The importance of polarization is further emphasized by the large RMSDs associated with the ff94 fixed point-charge potential, which averages at 33.8 kJ/mol. The polarizable AMOEBA potential performs better than the CP 3 , with an average RMSD of only 7.8 kJ/mol. The improved accuracy exhibited by AMOEBA is likely related to the inclusion of higher-order multipoles.