J. Phys. IV France
Volume 10, Numéro PR5, March 2000
The 1999 International Conference on Strongly Coupled Coulomb Systems
Page(s) Pr5-3 - Pr5-16
The 1999 International Conference on Strongly Coupled Coulomb Systems

J. Phys. IV France 10 (2000) Pr5-3-Pr5-16

DOI: 10.1051/jp4:2000501

Path integral Monte Carlo simulations for fermion systems : Pairing in the electron-hole plasma

J. Shumway and D. M. Ceperley

National Center for Supercomputing Applications and Department of Physics, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, U.S.A.

We review the path integral method wherein quantum systems are mapped with Feynman's path integrals onto a classical system of "ring-polymers" and then simulated with the Monte Carlo technique. Bose or Fermi statistics correspond to possible "cross-linking" of polymers. As proposed by Feynman, superfluidity and Bose condensation result from macroscopic exchange of bosons. To map fermions onto a positive probability distribution, one must restrict the paths to lie in regions where the fermion density matrix is positive. We discuss a recent application to the two-component electron-hole plasma. At low temperature excitons and bi-excitons form. We have used nodal surfaces incorporating paired fermions and see evidence of a Bose condensation in the energy, specific heat and superfluid density. In the restricted path integral picture, pairing appears as intertwined electron-hole paths. Bose condensation occurs when these intertwined paths wind around the periodic boundaries.

© EDP Sciences 2000