Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Formation energy and interaction of point defects in two-dimensional
  colloidal crystals   The manipulation of individual colloidal particles using optical tweezers has
allowed vacancies to be created in two-dimensional (2d) colloidal crystals,
with unprecedented possibility of real-time monitoring the dynamics of such
defects (Nature {\bf 413}, 147 (2001)). In this Letter, we employ molecular
dynamics (MD) simulations to calculate the formation energy of single defects
and the binding energy between pairs of defects in a 2d colloidal crystal. In
the light of our results, experimental observations of vacancies could be
explained and then compared to simulation results for the interstitial defects.
We see a remarkable similarity between our results for a 2d colloidal crystal
and the 2d Wigner crystal (Phys. Rev. Lett. {\bf 86}, 492 (2001)). The results
show that the formation energy to create a single interstitial is $12% - 28%$
lower than that of the vacancy. Because the pair binding energies of the
defects are strongly attractive for short distances, the ground state should
correspond to bound pairs with the interstitial bound pairs being the most
probable.

13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math