0000000000589999
AUTHOR
Irwin Oppenheim
Microscopic theory for hopping transport in glass-forming liquids: mode coupling corrections
Abstract By introducing an order parameter that describes the geometry of clusters of particles, Liu and Oppenheim [Physica A 247 (1997) 183] developed a microscopic theory for hopping transport in glass-forming liquids. In this work we bring this theory within the frame of mode coupling theories in the highly viscous regime. We calculate corrections to the effective longitudinal viscosity that affect its long-time dynamical behavior. Nevertheless, the relation between the longitudinal viscosity and the hopping kernel is not qualitatively altered by mode coupling.
Event-Driven Simulation of the Dynamics of Hard Ellipsoids
We introduce a novel algorithm to perform event-driven simulations of hard rigid bodies of arbitrary shape, that relies on the evaluation of the geometric distance. In the case of a monodisperse system of uniaxial hard ellipsoids,we perform molecular dynamics simulations varying the aspect-ratio X0 and the packing fraction phi. We evaluate the translational Dtrans and the rotational Drot diffusion coefficient and the associated isodiffusivity lines in the phi-X0 plane. We observe a decoupling of the translational and rotational dynamics which generates an almost perpendicular crossing of the Dtrans and Drot isodiffusivity lines. While the self intermediate scattering function exhibits stret…
On the nature of slow β-relaxation in supercooled liquids
We propose a model for reorientational motions of molecules associated with secondary beta-relaxation in supercooled liquids. The secondary relaxation is attributed to relaxation within a given local minimum, while the primary relaxation is attributed to transitions between distinct free-energy minima. We find that (i) at the temperature where the peak frequency of the extrapolated beta-relaxation intersects the alpha-relaxation, the actual and the extrapolated spectra differ in their time constants by approximately one decade; (ii) there is no clear division between the imaginary part of the dielectric susceptibility for the alpha- and the beta-relaxation for temperatures larger than 1.1 T…