Finite-size scaling of helix-coil transitions in poly-alanine studied by multicanonical simulations

We report results from multicanonical simulations of poly-alanine. Homopolymers of up to 30 amino acids were considered and various thermodynamic quantities as a function of temperature calculated. We study the nature of the observed helix-coil transition and present estimates for critical exponents.Comment: to appear in J.Chem.Phys. (Jan 99

Thermodynamics and Kinetics of Folding of a Small Peptide

We study the thermodynamics and kinetics of folding for a small peptide. Our data rely on Monte Carlo simulations where the interactions among all atoms are taken into account. Monte Carlo kinetics is used to study folding of the peptide at suitable temperatures. The results of these canonical simulations are compared with that of a generalized-ensemble simulation. Our work demonstrates that concepts of folding which were developed in the past for minimalist models hold also for this peptide when simulated with an all-atom force field

Configuration Space for Random Walk Dynamics

Applied to statistical physics models, the random cost algorithm enforces a Random Walk (RW) in energy (or possibly other thermodynamic quantities). The dynamics of this procedure is distinct from fixed weight updates. The probability for a configuration to be sampled depends on a number of unusual quantities, which are explained in this paper. This has been overlooked in recent literature, where the method is advertised for the calculation of canonical expectation values. We illustrate these points for the $2d$ Ising model. In addition, we proof a previously conjectured equation which relates microcanonical expectation values to the spectral density.Comment: Various minor changes, appendix added, Fig. 2 droppe

Yang-Lee zeros and the helix-coil transition in a continuum model of polyalanine

We calculate the Yang-Lee zeros for characteristic temperatures of the helix-coil transition in a continuum model of polyalanine. The distribution of these zeros differs from predictions of the Zimm-Bragg theory and supports recent claims that polyalanine exhibits a true phase transition. New estimates for critical exponents are presented and the relation of our results to the Lee-Yang theorem is discussed.Comment: 15 pages and 5 figure