Quantum Monte Carlo Studies of the Holstein Model
In this paper we study the competition between superconducting and charge density wave (CDW) formation in a system of interacting electrons and phonons by solution of the Eliashberg equations and by quantum Monte Carlo. We show that within the Eliashberg formalism, self energy corrections suppress the pair field susceptibility at high temperatures and that only below a certain cross-over temperature does one see enhancement. By conducting simulations at these low temperatures, we report the first observation of enhanced superconducting susceptibilities in numerical simulations of a model with dynamic electron-electron interactions.
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