Brownian motion of a nano-colloidal particle: the role of the solvent

• DOI: 10.1039/c5cp02777b
• Publication Date: 2015-06-26T13:03:45Z
• Authors: Alexis Torres-Car...; Salvador Herrera-...; Ramón Castañeda-P...
• Keywords: Brownian dynamics; Kernel (algebra); Momentum (technical analysis); Langevin dynamics; Particle (ecology); Langevin equation

Brownian motion is a feature of colloidal particles immersed in liquid-like environment. Usually, it can be described by means the generalised Langevin equation (GLE) within framework Mori theory. In principle, all quantities that appear GLE calculated from molecular information whole system, i.e., colloids and solvent molecules. this work, extensive Molecular Dynamics simulations, we study effects microscopic details thermodynamic state on movement single nano-colloid. particular, consider two-dimensional model system which mass size colloid are two one orders magnitude, respectively, larger than ones associated with The latter interact via Lennard-Jones-type potential to tune nature solvent, either repulsive or attractive. We choose linear momentum particle as observable interest order fully describe framework. particularly focus diffusion at different densities temperature regimes: high low (near critical point) temperatures. To reach our goal, have rewritten second kind Volterra integral compute memory kernel real space. With kernel, evaluate momentum-fluctuating force correlation function, particular relevance since allows us establish when stationarity condition has been reached. Our findings show even temperatures, attractive interaction among molecules induce important changes dynamics. Additionally, near point, dynamical scenario becomes more complex; functions decay slowly an extended time window, however, seems only function density. Thus, explicit inclusion description better understand behaviour those states region without any further approximation. This useful elaborate realistic descriptions take into account host medium.