34 research outputs found
{\em Ab initio} Quantum Monte Carlo simulation of the warm dense electron gas in the thermodynamic limit
We perform \emph{ab initio} quantum Monte Carlo (QMC) simulations of the warm
dense uniform electron gas in the thermodynamic limit. By combining QMC data
with linear response theory we are able to remove finite-size errors from the
potential energy over the entire warm dense regime, overcoming the deficiencies
of the existing finite-size corrections by Brown \emph{et al.}~[PRL
\textbf{110}, 146405 (2013)]. Extensive new QMC results for up to
electrons enable us to compute the potential energy and the
exchange-correlation free energy of the macroscopic electron gas with
an unprecedented accuracy of . A comparison of our new data to the recent parametrization of
by Karasiev {\em et al.} [PRL {\bf 112}, 076403 (2014)] reveals
significant deviations to the latter
Accurate exchange-correlation energies for the warm dense electron gas
Density matrix quantum Monte Carlo (DMQMC) is used to sample exact-on-average
-body density matrices for uniform electron gas systems of up to 10
matrix elements via a stochastic solution of the Bloch equation. The results of
these calculations resolve a current debate over the accuracy of the data used
to parametrize finite-temperature density functionals. Exchange-correlation
energies calculated using the real-space restricted path-integral formalism and
the -space configuration path-integral formalism disagree by up to
\% at certain reduced temperatures and densities . Our calculations confirm the accuracy of the configuration
path-integral Monte Carlo results available at high density and bridge the gap
to lower densities, providing trustworthy data in the regime typical of
planetary interiors and solids subject to laser irradiation. We demonstrate
that DMQMC can calculate free energies directly and present exact free energies
for and .Comment: Accepted version: added free energy data and restructured text. Now
includes supplementary materia