MULTI-SCALING PROPERTIES OF PHASE SEGREGATION IN QUENCHED BINARY FLUIDS - EVIDENCE FROM SIMULATIONS

The phase separation process in two-dimensional binary fluid systems i s investigated using molecular dynamics for almost 20 000 particles. P revious works from the same authors have shown that the late-stage coa rsening regime at critical volume fractions is described by power laws whose exponents are dependent on particle-particle interactions and o n temperature in a non-universal way. At the low-temperature region, h owever, the emergence of a three-phase regime of percolating domains w ith atoms of type-A, type-B and voids, invalidates the single-length s cale invariance. We argue in terms of a multiple-length scale analysis . In particular, for the case we studied with symmetric molecular pair potentials we propose two divergent length scales to characterize the dynamic process: one associated to the average size of equal-atom dom ains and the other related to the average size of undistinguishable-at om domains. Two different growth exponents can be inferred in such a c ase but the system does not exhibit scale invariance. (C) 1998 Elsevie r Science B.V. All rights reserved.