Simulation study of random sequential deposition of binary mixtures of lattice animals on a three-dimensional cubic lattice

Abstract

Random sequential adsorption of mixtures of objects of various shapes on a three-dimensional (3D) cubic lattice is studied numerically by means of Monte Carlo simulations. Depositing objects are ‘lattice animals’, made of a certain number of nearest neighbor sites on a lattice. We analyzed binary mixtures composed of shapes of equal size, n = 3, 4, 5. We concentrate here on the influence of geometrical properties of the shapes on the jamming coverage θ J and on the temporal evolution of the density θ(t). The approach of the coverage θ(t) to the jamming limit θ J is found to be exponential, θ J − θ(t) ∼ exp(−t/σ), both for the mixtures and their components. The values of the relaxation time σ are determined by the number of different orientations m that lattice animals can take when placed on a cubic lattice. The value of the relaxation time σ for a mixture is approximately twice the relaxation time for the pure component shape with a larger number m of possible orientations. Depending on the local geometry of the objects making the mixture, the jamming coverage of a mixture θ J can be either greater than both single-component jamming coverages or it can be in between these values. The first case is the most common, while in the second case, the jamming density of the mixture is very close to the higher jamming density for the pure component shapes. For a majority of the investigated mixtures, a component with a larger number of orientations m has a larger value of the fractional jamming density.