title: Imaginary time density-density correlations for two-dimensional electron gases at high density.
abstract: We evaluate imaginary time density-density correlation functions for two-dimensional homogeneous electron gases of up to 42 particles in the continuum using the phaseless auxiliary field quantum Monte Carlo method. We use periodic boundary conditions and up to 300 plane waves as basis set elements. We show that such methodology, once equipped with suitable numerical stabilization techniques necessary to deal with exponentials, products, and inversions of large matrices, gives access to the calculation of imaginary time correlation functions for medium-sized systems. We discuss the numerical stabilization techniques and the computational complexity of the methodology and we present the limitations related to the size of the systems on a quantitative basis. We perform the inverse Laplace transform of the obtained density-density correlation functions, assessing the ability of the phaseless auxiliary field quantum Monte Carlo method to evaluate dynamical properties of medium-sized homogeneous fermion systems.
authors.affiliation: Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Motta
authors.affiliation: Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy.
authors.forename: D E
authors.initials: DE
authors.lastname: Galli
authors.affiliation: IOM-CNR DEMOCRITOS National Simulation Center and SISSA, Via Bonomea 265, 34136 Trieste, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Moroni
authors.affiliation: Department of Physics, College of William and Mary, Williamsburg, Virginia 23187-8795, USA.
authors.forename: E
authors.initials: E
authors.lastname: Vitali