Biomedical subjects

Markus Holzmann

Publications and source records attributed to Markus Holzmann.

3 recordsLinked to original sources

PubMed2006

Finite-size error in many-body simulations with long-range interactions.

We discuss the origin of the finite-size error of the energy in many-body simulation of systems of charged particles and we propose a correction based on the random-phase approximation at long wavelengths. The correction is determined mainly by the collective charge oscillations of the interacting system. Finite-size corrections, both on kinetic and potential energy, can be calculated within a single simulation. Results are presented for the electron gas and silicon.

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PubMed2004

Coupled electron-ion monte carlo calculations of dense metallic hydrogen.

We present an efficient new Monte Carlo method which couples path integrals for finite temperature protons with quantum Monte Carlo calculations for ground state electrons, and we apply it to metallic hydrogen for pressures beyond molecular dissociation. We report data for the equation of state for temperatures across the melting of the proton crystal. Our data exhibit more structure and higher melting temperatures of the proton crystal than do Car-Parrinello molecular dynamics results. This method fills the gap between high temperature electron-proton path integral and ground state diffusion Monte Carlo methods and should have wide applicability.

Journal Article↗

PubMed2003

Condensate density and superfluid mass density of a dilute Bose-Einstein condensate near the condensation transition.

We derive via diagrammatic perturbation theory the scaling behavior of the condensate and superfluid mass density of a dilute Bose gas just below the condensation temperature, T(c). Sufficiently below T(c) particle excitations are described by mean field (Bogoliubov). Near T(c), however, mean field fails, and the system undergoes a second order phase transition, rather than first order as predicted by Bogoliubov theory. Both condensation and superfluidity occur at the same T(c), and have similar scaling functions below T(c), but different finite size scaling at T(c) to leading order in the system size. A self-consistent two-loop calculation yields the condensate fraction critical exponent, 2beta approximately 0.66.

Journal Article↗