Secondary relaxation in a supercooled binary mixture

Abstract

We investigate the structural relaxation in a binary fluid over the time scales of β-relaxation regime. For this we have used a recently proposed self-consistent mode-coupling theory (MCT) formulated from the fluctuating nonlinear hydrodynamics approach. We have considered here both the hard sphere as well as the Kob-Andersen Lennard-Jones1 binary mixtures. From the solution of the MCT equations obtained here the initial power law decay t^-a appears to be very weak. For the later part of the β-relaxation regime, the density correlation functions follow von Schweidler (VS) power law decay t^b. The validity of the so-called factorization property of the MCT over the β-relaxation is also analyzed. We find the exponent b to be in qualitative agreement with the findings from the computer simulations of the same system by Kob and Andersen.