Investigation of thermodynamic properties of lattice and off-lattice models for proteins and polymers

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The understanding of the thermodynamic behaviour of molecular chains with finite length is of extraordinary importance, since for heteropolymers the identification of the sequence-dependent classes of conformational states is quite difficult. Our recently developed multicanonical chain-growth method is capable to sample lattice heteropolymers at almost all temperatures. By applying it to simple lattice models for proteins, the relationship between sequence and conformation shall be analysed as well as fluctuations of energetic and structural quantities being indicators of conformational rearrangements of the monomers. This is to be carried over to off-lattice models, for which multicanonical sampling and a suitably adapted chaingrowth algorithm are applied. For these models we focus our attention to the study of the glass-like behaviour at low temperatures. For its adequate description, suitable system or "order" parameters, such as the structural overlap parameter, have to be introduced and studied. Furthermore, the application of our method to finite-length lattice homopolymers with (pseudo-)first-order-like transitions in d größer als 3 dimensions is intriguing, since the algorithm circumvents conformational barriers associated with less-favoured states.