State populations. Macrostate populations from a 100-microstate MSM show a wide range of predictions across the nine force fields (Figure ). In terms of predicting native state populations, OPLS-aa (56%) and AMBER99SBnm1-ildn (69%) perform the best, closely followed by AMBER99SB (52%). Interestingly, AMBER99SB-ildn (23%), the same force field with modified side chain torsions, overstabilizes the misfolded state over the native state.