Jean-Pierre Hansen — Page 2

arXiv1996

Binary friction tensor for Brownian particles : overcoming spurious finite-size effects

Starting from a careful analysis of the coupled Langevin equations for two interacting Brownian particles, we derive a method for extracting the binary friction tensor from the correlation function matrix of the instantaneous forces exerted by the bath particles on the fixed Brownian particles, and from the relaxation of the total momentum of the bath in a {\it finite} system. The general methodology, which circumvents the pitfalls associated with the inversion of the thermodynamic and long time limits, is applied to the case of two Brownian hard spheres in a bath of light spheres.

cond-mat↗

arXiv1996

Statistical Properties of the Dense Hydrogen Plasma: an ab initio Molecular Dynamics Investigation

The metallic regime of the hydrogen plasma is studied by ab initio Molecular Dynamics simulations, for classical protons and fully degenerate electrons, in the strong coupling regime of the protons. The breakdown of linear screening observed for decreasing density gives rise to a surprisingly rich low-temperature phase diagram, showing in particular a dramatic drop of the melting temperature of the proton crystal. Extensive dynamical simulations reveal the remarkable persistence of a weakly damped high-frequency ion acoustic mode (plasmon-like), even under conditions of strong electron screening. This collective mode should disappear in the molecular phase, thus providing a probe for the metal-insulator transition in a region of parameters where experiment is difficult to achieve. Finite-size effects arising in the simulation of liquid metals are discussed. The status of the dense Hydrogen matter is extensively reviewed in the introduction.

mtrl-th↗