(color online) Folding landscape of 1L2Y along two given collective variables at 300 K. (a), (c) The fraction of native contact and the correctness of secondary structure. (d), (d) The fraction of native contact and the backbone RMSD (reference is the native structure). The energy is in units of kcal/mol. The free energies of both force fields are constructed by the Markov state model using multiple trajectories. The initial conformations are drawn from a short replica exchange simulation and it contains several nearly folded structures which can enhance the bridging between the folded and the intermediate states in normal simulation.