Toward a Markov model approach to evaluating protein force fields, McKiernan et al. built Markov models of conformational dynamics from MD trajectories of the chignolin variant CLN025 simulated in AMBER-FB15 56 /TIP3P-FB, 57 AMBER99SB-ildn 6 /TIP3P and CHARMM22* 12 /mTIP3P 53 near the melting temperature of CLN025, at 340 K. They employed a projection MSM approach that forecasts new data onto a completed reference model, which standardizes microstate assignments across force fields. They found that while all force fields follow similar free energy surfaces, AMBER99SB-ildn and CHARMM22* overstabilize the native state.