Diffusion on a one-dimensional sawtooth lattice with the nearest and the next nearest neighbor interactions

The diffusion of particles adsorbed on a homogeneous one-dimensional sawtooth lattice with the nearest neighbor and the next nearest neighbor interactions between the particles is investigated using a theoretical approach and the kinetic Monte Carlo simulations. I have derived the analytical expressions for the diffusion coefficients. The calculated concentration dependencies of the coefficients have been compared with the numerical data generated by the simulations. The comparison reveals an interesting peculiarity of the particle diffusion. The lateral interactions induce correlations in the successive jumps of the particles. The thorough investigations of the dependencies clearly demonstrate how with the strengthening of the interactions the classical uncorrelated jumps are gradually replaced by the sequences of the correlated jumps. This behavior principally differs from the usual diffusion of particles in the homogeneous one-dimensional systems. It is an interesting and unexpected novelty of this system. Another uncommon feature of this model is a rich variety of the 'diffusion coefficients'. There are four combinations of the interaction parameter signs, and every combination has its own specific behavior of the particle diffusion, qualitatively opposite from the other combinations. Also, it should be noted a quite unusual result. In the homogeneous lattice gas system (all sites have an equal depth) with the strong, repulsive nearest neighbor and attractive next nearest neighbor interactions the diffusion is perfectly described by the diffusion coefficients derived for the heterogeneous lattices with deep and shallow sites. It is a direct evidence of the specific mode of the particle migration when the correlated pairs of jumps give the main contribution to the diffusion coefficients.