Dynamic susceptibility in a supercooled liquid: a molecular dynamics study

Abstract

Molecular dynamics (MD) simulations have been carried out on a two-component Lennard-Jones system, quenched into supercooled and amorphous states. The results for the time-dependence of the self-part of the density autocorrelation function, F q s( t), show two different slow relaxation processes, where the slowest (α-relaxation) can be represented by a stretched exponential, A exp[−( t τ rel ) β] . The second slow relaxation process (β-relaxation) is seen as a broad feature in the imaginary part of the dynamic susceptibility X q ″s( ω). Comparison with a recent non-linear mode coupling theory for the liquid-glass transition problem is made.