ROTATIONAL CORRELATION-FUNCTIONS AND APPARENTLY ENHANCED TRANSLATIONAL DIFFUSION IN A FREE-ENERGY LANDSCAPE MODEL FOR THE ALPHA-RELAXATION IN GLASS-FORMING LIQUIDS

We explore a simple model for supercooled liquids in which reorientati onal and translational motions are inherently coupled to the structura l relaxation. Several controversial aspects of the molecular motion in glass-forming materials are naturally resolved within the framework o f our model. These include the geometry of the molecular reorientation s as well as the apparent enhancement of translational diffusion. The breakdown of the Stokes-Einstein relation is thus explained without as suming the existence of local diffusion coefficients.