DOI: 10.1051/jp1:1992152
J. Phys. I France 2 (1992) 393-400

Strong correlations and electron-phonon coupling in high-temperature superconductors: a quantum Monte Carlo study

I. Morgenstern^{1, 2, 3}, M. Frik^{1, 4} and W. von der Linden<sup>1, 5

1</sup>  HLRZ, c/o KFA Jülich, Postfach 1913, D-5170 Jülich, Germany
²  Institute for Theoretical Physics, University of Regensburg, D-8400 Regensburg, Germany
³  IBM Research Lab. Zurich, Saeumerstr. 4, CH-8803 Ruschlikon, Switzerland
⁴  Institute for Theoretical Physics, University of Groningen, PO-Box 800, NL-9700 AV Groningen, The Netherlands
⁵  Max-Planck Institute for Plasma Physics, Boltzmannstr.2, D-8046 Garching, Germany

(Received 9 December 1991, accepted in final form 10 January 1992)

Abstract
We present quantum simulation studies for a system of strongly correlated fermions coupled to local anharmonic phonons. The Monte Carlo calculations are based on a generalized version of the Projector Quantum Monte Carlo Method allowing a simultaneous treatment of fermions and dynamical phonons. The numerical simulations yield exact results in the electron-phonon parameter regime relevant for high- superconductivity, which is not accessible by perturbative methods like Eliashberg-Theory. The class of electron-phonon-models covered in the simulations describes superconductivity exhibiting several features of the new high- materials.

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