Title | Tight binding within the fourth moment approximation: Efficient implementation and application to liquid Ni droplet diffusion on graphene |
Publication Type | Journal Article |
Year of Publication | 2011 |
Authors | Los J.H, Bichara C, Pellenq RJean-Marc |
Journal | Physical Review B |
Volume | 84 |
Issue | 8 |
Pagination | Article Number: 085455 |
Date Published | Aug-31-2011 |
ISSN | 1098-0121 |
Abstract | Application of the fourth moment approximation (FMA) to the local density of states within a tight binding description to build a reactive, interatomic interaction potential for use in large scale molecular simulations, is a logical and significant step forward to improve the second moment approximation, standing at the basis of several, widely used (semi-)empirical interatomic interaction models. In this paper we present a sufficiently detailed description of the FMA and its technical implications, containing the essential elements for an efficient implementation in a simulation code. Using a recent, existing FMA-based model for C-Ni systems, we investigated the size dependence of the diffusion of a liquid Ni cluster on a graphene sheet and find a power law dependence of the diffusion constant on the cluster size (number of cluster atoms) with an exponent very close to −2/3, equal to a previously found exponent for the relatively fast diffusion of solid clusters on a substrate with incommensurate lattice matching. The cluster diffusion exponent gives rise to a specific contribution to the cluster growth law, which is due to cluster coalescence. This is confirmed by a simulation for Ni cluster growth on graphene, which shows that cluster coalescence dominates the initial stage of growth, overruling Oswald ripening. |
DOI | 10.1103/PhysRevB.84.085455 |
Short Title | Phys. Rev. B |