Kimmo Kaski

Kinetics of island growth in models of physisorbed and chemisorbed systems

Abstract A brief review is given of recent computer simulation studies of the kinetics of island formation in submonolayers of physisorbed and chemisorbcd systems. Examples include models of O/W(112). O/W(110) and orientational ordering in N2 on graphite.

COMPUTER SIMULATIONS OF DOMAIN GROWTH

A review is given of the use of lattice gas models to simulate the kinetics of first-order phase transitions. In particular we discuss domain growth in the non-conserved Ising model, a prototypical example which simulates, for example, the order-disorder transition in binary alloys. Other models will also be discussed.

Morphological Changes of Small Viscous Droplets under Spreading

The dynamics of spreading of viscous non-volatile fluid droplets on surfaces is modelled using a solid-on-solid model, which is studied with Monte Carlo simulations. Tendencies to dynamical layering and surface attraction are in part embedded into the effective dynamics of the model. This allows a description of the spreading process with a single parameter, which strongly influences the morphology of the droplets. The results qualitatively reproduce many experimentally observed density profiles for polymeric fluids, including rounded droplet shapes and dynamical layering.

Dynamical scaling in the order-disorder herringbone transition☆

Abstract The development of orientational order in an anisotropic planar rotor model has been studied by Monte Carlo methods. The order develops following an instantaneous quench from a high temperature, disordered phase to an unstable low temperature state in which a threefold degenerate herringbone phase is the equilibrium state. The model describes the orientational properties of N 2 molecules physisorbed on the hexagonal graphite surface and with some modifications the ordering of certain smectic phases in liquid crystals. Both the dynamical structure factor and average domain size have been determined. The structure factor is shown to satisfy dynamical scaling. The growth laws for three different measures of “domain size” are all shown to be consistent with the Allen-Cahn theory. This interpretation of the data is in disagreement with an earlier analysis of domain growth for this model.

RANDOM FIELD ISING MODEL: COMPUTER SIMULATIONS OF DOMAIN GROWTH

We have simulated the two-dimensional ferromagnetic Ising model in a random magnetic field with spin-flip dynamics. After the system is deeply quenched into the unstable region of the zero-field phase diagram, we observe novel dynamical behaviour for the average size of the growing domains. Recent theoretical predictions are discussed.