Dresden 2003 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.99: Poster

Donnerstag, 27. März 2003, 15:30–18:00, P1

Phase transitions of classical and quantum hard disks in external periodic potentials: a Path Integral MC Study — •Wolfram Strepp and Peter Nielaba — Lehrstuhl für Theoretische Physik, Fachbereich Physik, Universität Konstanz, D-78457 Konstanz

Hard and soft disks in external periodic potentials show rich phase diagrams including freezing and melting transitions when the density of the system is varied. Based on extensive Monte Carlo simulations, we report analyses of various thermodynamic quantities like the order parameter, its Binder-cumulants etc. in order to map the phase diagram of the system for various values of the density and the amplitude of the external potential. Depending on the particle potential, we find clear indication of a reentrant liquid phase over a significant region of the parameter space, which is similar to the behaviour of charge-stabilized colloids in an external modulating field. In order to quantify the quantum effect of the finite particle masses on the phase diagram, we investigated the system by PIMC. We find a increased reentrance region which can be even larger than the freezing region. A possible explanation of this effect is presented.

[1] W. Strepp, S. Sengupta, P. Nielaba, Phys. Rev. E 63, 046106 (2001).

[2] W. Strepp, S. Sengupta, P. Nielaba, Phys. Rev. E 66, 056109 (2002).

[3] C. Bechinger et al., Phys. Rev. Lett. 86, 930 (2001).

[4] E. Frey et al., Phys. Rev. Lett. 83, 2977 (1999).