A new generalized-ensemble algorithm: multicanonical–multioverlap algorithm

We introduce a new generalized-ensemble algorithm, which we refer to as the multicanonical–multioverlap algorithm. By utilizing a non-Boltzmann weight factor, this method realizes a random walk in the multi-dimensional, energy-overlap space and explores widely in the configurational space including specific configurations, where the overlap of a configuration with respect to a reference state is a measure for structural similarity. We apply the multicanonical–multioverlap molecular dynamics (MD) method to a penta peptide, Met-enkephalin, in vacuum as a test system. We also apply the multicanonical and multioverlap MD methods to this system for the purpose of comparisons. We see that the multicanonical–multioverlap MD method realizes effective sampling in the configurational space including specific configurations more than the other two methods.