Computer-Simulation Dynamics of an Unstable Two-Dimensional Fluid: Time-Dependent Morphology and Scaling

From an isothermal molecular-dynamics experiment of an unstable two-dimensional fluid undergoing phase separation, two principal growth regimes are observed: (1) spinodal decomposition with a wavelike morphology followed by (2) a transition to cluster formation and growth due to atomic condensation and cluster coagulation. The time-dependent power-law behavior for the second growth regime is 0.5, in contrast to a constant-energy simulation which yields a power-law behavior of 0.33. Details of the phase-separation dynamics are discussed and compared with theory.