title: Interaction picture density matrix quantum Monte Carlo.
abstract: The recently developed density matrix quantum Monte Carlo (DMQMC) algorithm stochastically samples the N-body thermal density matrix and hence provides access to exact properties of many-particle quantum systems at arbitrary temperatures. We demonstrate that moving to the interaction picture provides substantial benefits when applying DMQMC to interacting fermions. In this first study, we focus on a system of much recent interest: the uniform electron gas in the warm dense regime. The basis set incompleteness error at finite temperature is investigated and extrapolated via a simple Monte Carlo sampling procedure. Finally, we provide benchmark calculations for a four-electron system, comparing our results to previous work where possible.
authors.affiliation: Department of Physics, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: Fionn D
authors.initials: FD
authors.lastname: Malone
authors.affiliation: University Chemical Laboratory, Cambridge University, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
authors.forename: N S
authors.initials: NS
authors.lastname: Blunt
authors.affiliation: Department of Physics, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: James J
authors.initials: JJ
authors.lastname: Shepherd
authors.affiliation: Department of Physics, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: D K K
authors.initials: DK
authors.lastname: Lee
authors.affiliation: Department of Physics, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: J S
authors.initials: JS
authors.lastname: Spencer
authors.affiliation: Department of Physics, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.
authors.forename: W M C
authors.initials: WM
authors.lastname: Foulkes