Authors

G. Nandipati; A. Kara; S. I. Shah;T. S. Rahman

Comments

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Abbreviated Journal Title

Phys. Rev. B

Keywords

MONTE-CARLO SIMULATIONS; CLUSTER COALESCENCE; BROWNIAN-MOTION; METAL-SURFACES; STEP DYNAMICS; AG CLUSTERS; DIFFUSION; AG(111); SI(001); ADATOM; Physics, Condensed Matter

Abstract

We present here a detailed analysis of the shapes of two-dimensional Ag islands of various sizes observed during the early stages of coarsening on the Ag(111) surface, using kinetic Monte Carlo (KMC) simulations, and show that selectivity is due to the formation of kinetically stable island shapes that survive longer than nonselected sizes, which decay into nearby selected sizes. The stable shapes have a closed-shell structure-one in which every atom on the periphery has at least three nearest neighbors. These findings further explain our earlier study in which we found that in the early stages coarsening proceeds as a sequence of selected island sizes resulting in peaks and valleys in the island size distribution [G. Nandipati, A. Kara, S. I. Shah, and T. S. Rahman, J. Phys.: Condens. Matter 23, 262001 (2011)]. This selectivity is dictated by the relative energetics of edge-atom diffusion and detachment and attachment processes and by the large activation barrier for kink detachment. Our simulations were carried out using a very large database of processes identified by each atom's unique local environment using the self-learning KMC scheme. The activation barriers were calculated using semiempirical interaction potentials based on the embedded-atom method.

Journal Title

Physical Review B

Volume

88

Issue/Number

11

Publication Date

1-1-2013

Document Type

Article

Language

English

First Page

8

WOS Identifier

WOS:000323891100009

ISSN

1098-0121

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