Ludovic Berthier

Sep 17, 2024 | link.aps.org | Federico Ghimenti |Ludovic Berthier |Laboratoire Charles Coulomb

Abstract Exerting a nonequilibrium drive on an otherwise equilibrium Langevin process brings the dynamics out of equilibrium but can also speed up the approach to the Boltzmann steady state. Transverse forces are a minimal framework to achieve dynamical acceleration of the Boltzmann sampling. We consider a simple liquid in three space dimensions subjected to additional transverse pairwise forces, and quantify the extent to which transverse forces accelerate the dynamics.

Jul 10, 2024 | link.aps.org | Federico Ghimenti |Ludovic Berthier |Laboratoire Charles Coulomb

Equilibrium sampling of the configuration space in disordered systems requires algorithms that bypass the glassy slowing down of the physical dynamics. Irreversible Monte Carlo algorithms breaking detailed balance successfully accelerate sampling in some systems. We first implement an irreversible event-chain Monte Carlo algorithm in a model of continuously polydisperse hard disks.

Jun 13, 2024 | link.aps.org | Federico Ghimenti |Ludovic Berthier |Laboratoire Charles Coulomb

We explore the dynamics of a simple liquid whose particles, in addition to standard potential-based interactions, are also subjected to transverse forces preserving the Boltzmann distribution. We derive the effective dynamics of one and two tracer particles in the infinite-dimensional limit. We determine the amount of acceleration of the dynamics caused by the transverse forces, in particular in the vicinity of the glass transition.

Feb 7, 2024 | link.aps.org | Yoshihiko Nishikawa |Ludovic Berthier |Laboratoire Charles Coulomb

We numerically elucidate the microscopic mechanisms controlling the relaxation dynamics of a three-dimensional lattice glass model that has static properties compatible with the approach to a random first-order transition. At low temperatures, the relaxation is triggered by a small population of particles with low-energy barriers forming mobile clusters.

Dec 18, 2023 | link.aps.org | Ludovic Berthier |Laboratoire Charles Coulomb |Lensfield Road |Federico Ghimenti

Sampling the Boltzmann distribution using forces that violate detailed balance can be faster than with the equilibrium evolution, but the acceleration depends on the nature of the nonequilibrium drive and the physical situation. Here, we study the efficiency of forces transverse to energy gradients in dense liquids through a combination of techniques: Brownian dynamics simulations, exact infinite-dimensional calculation, and a mode-coupling approximation.