Dresden 2009 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 13: Statistical physics III (general)

DY 13.2: Talk

Tuesday, March 24, 2009, 15:00–15:15, ZEU 255

Ground states of 2d ± J Ising spin glasses via stationary Fokker-Planck sampling — •Oliver Melchert and Alexander K. Hartmann — Institut für Physik, Universität Oldenburg, Carl-von-Ossietzky Strasse 9-11, 26111 Oldenburg, Germany

We investigate the performance of the recently proposed stationary Fokker-Planck sampling method considering a combinatorial optimization problem from statistical physics. The algorithmic procedure relies upon the numerical solution of a linear second order differential equation that depends on a diffusion-like parameter D. We apply it to the problem of finding ground states of 2d Ising spin glasses for the ± J−Model. We consider square lattices with side length up to L=24 with two different types of boundary conditions and compare the results to those obtained by exact methods. A particular value of D is found that yields an optimal performance of the algorithm. We compare this optimal value of D to a percolation transition, which occurs when studying the connected clusters of spins flipped by the algorithm. Nevertheless, even for moderate lattice sizes, the algorithm has more and more problems to find the exact ground states. This means that the approach, at least in its standard form, seems to be inferior to other approaches like parallel tempering.