Quantum Monte Carlo simulations for disordered Bose systems
Interacting bosons in a random potential can be used to model {sup 3}He adsorbed in porous media, universal aspects of the superconductor-insulator transition in disordered films, and vortices in disordered type II superconductors. We study a model of bosons on a 2D square lattice with a random potential of strength V and on-site repulsion U. We first describe the path integral Monte Carlo algorithm used to simulate this system. The 2D quantum problem (at T=0) gets mapped onto a classical problem of strings or directed polymers moving in 3D with each string representing the world line of a boson. We discuss efficient ways of sampling the polymer configurations as well as the permutations between the bosons. We calculate the superfluid density and the excitation spectrum. Using these results we distinguish between a superfluid, a localized or ``Bose glass`` insulator with gapless excitations and a Mott insulator with a finite gap to excitations (found only at commensurate densities). We discover novel effects arising from the interpaly between V and U and present preliminary results for the phase diagram at incommensurate and commensurate densities.
- Research Organization:
- Argonne National Lab., IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 10136152
- Report Number(s):
- ANL/CP-75721; CONF-920292-1; ON: DE92010343
- Resource Relation:
- Conference: Workshop on recent developments in computer simulation studies in condensed matter physics,Athens, GA (United States),17-21 Feb 1992; Other Information: PBD: Mar 1992
- Country of Publication:
- United States
- Language:
- English
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SUPERCONDUCTIVITY AND SUPERFLUIDITY
HELIUM 4
SUPERFLUIDITY
BOSONS
PHASE STUDIES
TWO-DIMENSIONAL CALCULATIONS
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TYPE-II SUPERCONDUCTORS
MONTE CARLO METHOD
HAMILTONIANS
TEMPERATURE ZERO K
VORTICES
SUPERCONDUCTIVITY
665420
665411
BASIC SUPERCONDUCTIVITY STUDIES