Spatial correlations of particle displacements in a glass-forming liquid

We define a generic correlation function that quantifies the spatial correl ation of single-particle displacements in liquids and amorphous systems. We evaluate this function using computer simulations of an equilibrium glass- forming liquid, and show that the displacements of particles are spatially correlated over a range that grows with decreasing temperature as the glass transition is approached. (C) 1998 Elsevier Science B.V. All rights reserv ed.