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SYMC: Symposium Neue Entwicklungen in Quanten-Monte-Carlo-Simulationen

SYMC I: HV I

SYMC I.1: Hauptvortrag

Mittwoch, 24. März 1999, 14:30–15:00, Ger

Green’s Function Monte Carlo for Lattice Systems. — •J. M. J. van Leeuwen — Instituut–Lorentz, Leiden University, 2300 GA Leiden, The Netherlands

The Green’s Function Monte Carlo (GFMC) technique will be discussed for lattice systems. The method is efficient as long as there is no sign problem in the wavefunction such as occurs in fermion systems and frustrated spin systems. The Fixed Node approximation of Ceperley and Alder[1], avoiding the sign problem for a continuum systems, can be adapted to the lattice and made variational[2]. This reduces the quality of the approximation to that of the nodal structure of the guiding wavefunction. Compromises between the amount of effort put in the construction of the guiding wavefunction and the simulation time will be discussed, in particular with respect to the accuracy which can be achieved with the DMRG-method of White[3]. With the frustrated Heisenberg model as testground, the improvements of stochastic reconfiguration as proposed by Sorella[4] will be shown.

[1] D. M. Ceperley and B. J. Alder, Phys. Rev. Lett. 45, 566 (1980)

[2] H. J. M. van Bemmel et. al., Phys. Rev. Lett. 72 (1994) 2442

[3] S. R. White, Phys. Rev. Lett. 69, 2863 (1992)

[4] S. Sorella, Phys. Rev. Lett. 80 (1998) 4558