Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The crossover from collective motion to periphery diffusion for 2D
  adatom-islands on Cu(111)   The diffusion of two dimensional adatom islands (up to 100 atoms) on Cu(111)
has been studied, using the self-learning Kinetic Monte Carlo (SLKMC) method
[1]. A variety of multiple- and single-atom processes are revealed in the
simulations, and the size dependence of the diffusion coefficients and
effective diffusion barriers are calculated for each. From the tabulated
frequencies of events found in the simulation, we show a crossover from
diffusion due to the collective motion of the island to a regime in which the
island diffuses through periphery-dominated mass transport. This crossover
occurs for island sizes between 13 and 19 atoms. For islands containing 19 to
100 atoms the scaling exponent is 1.5, which is in good agreement with previous
work. The diffusion of islands containing 2 to 13 atoms can be explained
primarily on the basis of a linear increase of the barrier for the collective
motion with the size of the island.

16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph