Europhys. Lett.
Volume 71, Number 4, August 2005
Page(s) 646 - 650
Section Condensed matter: structural, mechanical and thermal properties
Published online 14 July 2005
Europhys. Lett., 71 (4), pp. 646-650 (2005)
DOI: 10.1209/epl/i2005-10122-3

A model for the generic alpha relaxation of viscous liquids

J. C. Dyre

Department of Mathematics and Physics (IMFUFA), "Glass and time" Danish National Research Foundation Centre for Viscous Liquid Dynamics Roskilde University - Postbox 260, DK-4000 Roskilde, Denmark

received 23 March 2005; accepted in final form 20 June 2005
published online 14 July 2005

Dielectric measurements on molecular liquids just above the glass transition indicate that alpha relaxation is characterized by a generic high-frequency loss varying as $\omega^{-1/2}$, whereas deviations from this come from one or more low-lying beta processes (Olsen et al. , Phys. Rev. Lett. 86 (2001) 1271). Assuming that long-wavelength fluctuations dominate the dynamics, a model for the dielectric alpha relaxation based on the simplest coupling between the density and dipole density fields is proposed here. The model, which is solved in second-order perturbation theory in the Gaussian approximation, reproduces the generic features of alpha relaxation.

64.70.Pf - Glass transitions.
77.22.Gm - Dielectric loss and relaxation.

© EDP Sciences 2005