Finite-Temperature Monte Carlo Calculations For Systems With Fermions

TL;DR

This paper introduces a quantum Monte Carlo method for simulating many-fermion systems at finite temperatures without sign decay, enabling large-scale and low-temperature calculations with accurate energy and correlation results.

Contribution

A novel approximate algorithm that eliminates sign decay in finite-temperature fermion simulations by constraining the fermion determinant.

Findings

Accurate energy calculations for the Hubbard model

Reliable correlation function results

Elimination of sign decay in Monte Carlo simulations

Abstract

We present a quantum Monte Carlo method which allows calculations on many-fermion systems at finite temperatures without any sign decay. This enables simulations of the grand-canonical ensemble at large system sizes and low temperatures. Both diagonal and off-diagonal expectations can be computed straightforwardly. The sign decay is eliminated by a constraint on the fermion determinant. The algorithm is approximate. Tests on the Hubbard model show that accurate results on the energy and correlation functions can be obtained.