Monte Carlo simulation on thermodynamic properties of a heteropolymer chain

The equilibrium thermodynamic properties of a heteropolymer chain of 4 hydr ophobic and 26 hydrophilic segments with Lennard-Jones interaction among se gments were studied by multicanonical Monte Carlo methods in a three-dimens ional off-lattice model. It is approved that the multicanonical algorithms provide us a practical way to accurately calculate thermodynamic properties of the chain at lower temperature. The collapse transition of a heteropoly mer chain cooled from higher temperature is able to be separated in three s teps: First, the hydrophobic segments associate together to form a hydropho bic core; then, the hydrophilic segments collapse on the surface of the cor e; finally, the heteropolymer chain reorganizes into its lowest energy stat e. (C) 2001 American Institute of Physics.