Dynamic Pair Correlations and Superadiabatic Forces in a Dense Brownian Liquid

Abstract

We study dynamic two-body correlation functions, i.e. the two-body density, the current-density correlator or van Hove current, and the current-current correlator in Brownian dynamics computer simulations of a dense Lennard-Jones bulk liquid. The dynamic decay of the correlation shells of the two-body density is examined in detail. Inner correlation shells decay faster than outer correlation shells, whereas outer correlation shells remain stable for increasing times. Within a dynamic test particle picture the mechanism is assumed to be triggered by the dislocation of the self particle, which releases the confinement of the surrounding correlation shells. We present a division of the van Hove current into an adiabatic and a superadiabatic contribution. The magnitude of the adiabatic van Hove current is found to exceed that of the total van Hove current, which is consistent with dynamic density functional theory overestimating the speed of the dynamics. The direction of the superadiabatic van Hove current opposes that of the total van Hove current. The current-current correlator reveals detailed insight in the collisions of the particles. We find a large static nearest-neighbor peak, which results from colliding particles and different dynamic peaks, that are attributed to consecutive collisions.

19 pages, 11 figures

References in corpus (14)

• Dynamic Density Functional Theory of Fluids
• Dynamical density functional theory and its application to spinodal decomposition
• The van Hove distribution function for Brownian hard spheres: dynamical test particle theory and computer simulations for bulk dynamics
• Power functional theory for Brownian dynamics
• Dynamics in inhomogeneous liquids and glasses via the test particle limit
• Superadiabatic forces in Brownian many-body dynamics
• Nonequilibrium Ornstein-Zernike relation for Brownian many-body dynamics
• Direct Observation in 3d of Structural Crossover in Binary Hard Sphere Mixtures
• Modeling diffusion in colloidal suspensions by dynamical density functional theory using fundamental measure theory of hard spheres
• Dynamical density functional theory for dense suspensions of colloidal hard spheres
• Dynamic correlations in Brownian many-body systems
• Particle Conservation in Dynamical Density Functional Theory
• Superadiabatic forces in the dynamics of the one-dimensional Gaussian core model
• Minimal Model for Dynamic Bonding in Colloidal Transient Networks

Cited by in corpus (11)

• Classical dynamical density functional theory: from fundamentals to applications
• Power functional theory for many-body dynamics
• Nonequilibrium phase behaviour from minimization of free power dissipation
• Perspective: How to overcome dynamical density functional theory
• Bulk dynamics of Brownian hard disks: Dynamical density functional theory versus experiments on two-dimensional colloidal hard spheres
• Universality in Driven and Equilibrium Hard Sphere Liquid Dynamics
• Order-preserving dynamics in one dimension -- single-file diffusion and caging from the perspective of dynamical density functional theory
• Dynamic Decay and Superadiabatic Forces in the van Hove Dynamics of Bulk Hard Sphere Fluids
• Reconsidering Power Functional Theory
• Metadensity functional learning for classical fluids: Regularizing with pair correlations
• Ballistic propagation of density correlations and excess wall forces in quenched granular media