MIDIT OFD CATS Modelling, Nonlinear Dynamics Optics and Fluid Dynamics Chaos and Turbulence Studies and Irreversible Thermodynamics Risø National Laboratory Niels Bohr Institute and Technical University of Denmark Building 128 Department of Chemistry Building 321 P.O. Box 49 University of Copenhagen DK-2800 Lyngby DK-4000 Roskilde DK-2100 Copenhagen Ø Denmark Denmark Denmark
by Kim Ørskov Rasmussen
Center for Nonlinear Sciences
Los Alamos, USA
Tuesday August 24, 1999, 15.00 h
at MIDIT, IMM Building 305, room 027
Abstract: The statistical mechanics of the discrete nonlinear Schrödinger equation is studied by means of analytic and numerical techniques. The lower bound of the Hamiltonian permits the construction of standard Gibbsian equilibrium measures for positive temperatures. Beyond the T=infinity line, we identify a phase transition, through a discontinuity in the partition function. The phase transition is demonstrated to manifest itself in the creation of breather-like localized excitations. The interrelation between the statistical mechanics and the nonlinear dynamics of the system is explored numerically both in the positive and in the negative temperature regimes.