Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Symmetry-induced gap opening in graphene superlattices   We study nxn honeycomb superlattices of defects in graphene. The considered
defects are missing p_z orbitals and can be realized by either introducing C
atom vacancies or chemically binding simple atomic species at the given sites.
Using symmetry arguments we show how it is possible to open a gap when
n=3m+1,3m+2 (m integer), and estimate its value to have an approximate
square-root dependence on the defect concentration x=1/n^2. Tight-binding
calculations confirm these findings and show that the induced-gaps can be quite
large, e.g. ~100 meV for x~10^{-3}. Gradient-corrected density functional
theory calculations on a number of superlattices made by H atoms adsorbed on
graphene are in good agreement with tight-binding results, thereby suggesting
that the proposed structures may be used in practice to open a gap in graphene.

31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
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The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph