8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Tue 611:23-14:00P9.61Incomplete equilibration of dense hard-sphere fluidsLuis Enrique Sanchez Diaz, 1 Pedro Ezequiel Ramirez Gonzalez, 1 and MagdalenoMedina Noyola 11 Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000, San Luis Potosi,MexicoThe self-consistent generalized Langevin equation (SCGLE) theory of colloid dynamics anddynamic arrest has been recently extended [1] to describe the irreversible evolution of the staticstructure factor and of the intermediate scattering function of a liquid in response to changes in theexternal macroscopic control parameters. This non-equilibrium theory has already been appliedto the description of the aging processes occurring in a suddenly quenched model colloidal liquidwith hard-sphere plus short-ranged attractive interactions [2]. Here we apply the same theory tothe description of the slow dynamics of incompletely equilibrated glass-forming liquids. For this,we consider the equilibration process of a hard-sphere fluid prepared in a non-equilibrium statewith the desired final volume fraction φ but with a prescribed non-equilibrium static structurefactor S 0 (k; φ) different from the equilibrium structure factor S eq (k; φ). The evolution of theα-relaxation time τα(k) and of the long-time self-diffusion coefficient DL as a function ofthe evolution time tw is then monitored for an array of volume fractions. For a given waitingtime the plot of τα(k; tw, φ) as a function of φ exhibits two regimes corresponding to samplesthat have fully equilibrated within this waiting time (φ < φ(c)(tw)) and to samples for whichequilibration is not yet complete (φ > φ(c)(tw)). This two-regime scenario is observed inmolecular dynamics simulations of incompletely equilibrated hard-sphere liquids and resemblesthe recent experimental observations of Brambilla et al. [3].[1] P. Ramírez-González and M. Medina-Noyola, J. Phys. : Condens. Matter 21 (2009)504103.[2] P. Ramírez-González and M. Medina-Noyola, Phys. Rev. E 82, 061504 (2010)[3] G. Brambilla et al. Phys. Rev. Lett. 102 (2009) 085703.61