LATE-STAGE PHASE-SEPARATION - DYNAMICS, SPATIAL CORRELATIONS, AND STRUCTURE FUNCTIONS

Particle coarsening in the late stage was investigated using numerical simulations. The multiparticle diffusion problem was solved using a m ultipole expansion method which is valid to an arbitrary order of the expansion. The simulations were performed using both monopole and mono pole plus dipole approximations. We found that the monopole approximat ion yields a good description of the diffusion field up to a volume fr action of approximately 0.1. Beyond this volume fraction, particle mig ration induced by interparticle diffusional interactions plays an impo rtant role. The simulations were performed using two different initial spatial distributions. Despite the different initial states of the sy stem, we find that the spatial correlation functions evolve to unique scaled time independent forms. These spatial correlation functions sho w that depletion zones exist between small particles and that the dens ity of small particles near large particles is less than that of a ran dom spatial distribution. A scaled time independent structure function similar to that observed experimentally was found. The slope of the s tructure function in a log-log plot is close to 4 at small wave number s and is -4 at very large wave numbers. Oscillations in the structure function, which are related to the spherical shape and size distributi on of particles, are present at large wave numbers. The rate constant of the cubic growth law and the scaled particle size distribution are also determined.