paper

Testing Mode-Coupling Theory for a Supercooled Binary Lennard-Jones Mixture II: Intermediate Scattering Function and Dynamic Susceptibility

arXiv:cond-mat/9505118 · doi:10.1103/PhysRevE.52.4134

Abstract

We have performed a molecular dynamics computer simulation of a supercooled binary Lennard-Jones system in order to compare the dynamical behavior of this system with the predictions of the idealized version of mode-coupling theory (MCT). By scaling the time by the temperature dependent -relaxation time , we find that in the -relaxation regime and , the coherent and incoherent intermediate scattering functions, for different temperatures each follows a -dependent master curve as a function of scaled time. We show that during the early part of the -relaxation, which is equivalent to the late part of the -relaxation, these master curves are well approximated by the master curve predicted by MCT for the -relaxation. This part is also fitted well by a power-law, the so-called von Schweidler law. We show that the effective exponent of this power-law depends on the wave vector if is varied over a large range. The early part of the -relaxation regime does not show the critical decay predicted by MCT. The -dependence of the nonergodicity parameter for and are in qualitative agreement with MCT. On the time scale of the late -relaxation the correlation functions show a Kohlrausch-Williams-Watt behavior (KWW). The KWW exponent is significantly different from the effective von Schweidler exponent . At low temperatures the -relaxation time shows a power-law behavior with a critical temperature that is the same as the one found previously for the diffusion constant [Phys. Rev. Lett. {\bf 73}, 1376 (1994)]. The critical exponent of this power-law and the von Schweidler exponent fulfill the connection proposed by MCT between these two quantities. We also show that the

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