COUPLING BETWEEN THE STRUCTURE AND SELF-DIFFUSION IN THE SUPERCOOLED LIQUID DYNAMICS REGIME

The process of self-diffusion of a tagged particle in a simple liquid composed of identical particles was investigated in the time window corresponding to the alpha-relaxation regime using the molecular dynamics simulation. The liquid explored in this study could be cooled, in an equilibrium way, to a state with singularly low diffusion rate where it exhibited clear signatures of supercooled dynamics, including non-exponential behaviour of its incoherent intermediate scattering function, F-s(Q,t). In order to analyze this behaviour, the exponential simple diffusion approximation of F-s(Q t) was subtracted, and the resulting difference was presented using a convenient dimensionless timescale, DQ(2)t, D being the self-diffusion coefficient. In this presentatioin, the non-exponential component of F-s(Q,t) was found to demonstrate strong non-monotonic Q-dependence correlating with the corresponding variation of the static structure factor.