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CPP: Chemische Physik und Polymerphysik

CPP 7: Computational Physics

CPP 7.3: Talk

Tuesday, March 25, 2003, 17:30–17:45, ZEU/160

Energy Density of Heteropolymers — •Michael Bachmann and Wolfhard Janke — Institut für Theoretische Physik, Universität Leipzig, Augustusplatz 10/11, 04109 Leipzig

We use the random walk Monte Carlo (MC) algorithm of Wang and Landau [1] to calculate the energy density of lattice proteins that fold under the influence of the nearest-neighbor interactions between the hydrohobic residues as regarded in the simple HP model [2]. The advantage of this method, which has originally been applied for simulating spin systems, is that it produces a locally flat histogram without introducing a temperature. Therefore a random walk through the energy space yields a very accurate estimate for the density of states which allows a calculation of all energy-dependent thermodynamic quantities. Thus, in contrast to conventional MC simulations, the free energy and the entropy can directly be determined. We compare our results with such from exact enumerations for short chain lengths as well as with results obtained with other MC techniques for longer sequences.
[1] F. Wang and D.P. Landau, Phys. Rev. Lett. 86, 2050 (2001).
[2] K.F. Lau and K.A. Dill, Macromolecules 22, 3986 (1989).