Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Understanding adsorption of hydrogen atoms on graphene   Adsorption of hydrogen atoms on a single graphite sheet (graphene) has been
investigated by first-principles electronic structure means, employing
plane-wave based, periodic density functional theory. A reasonably large 5x5
surface unit cell has been employed to study single and multiple adsorption of
H atoms. Binding and barrier energies for sequential sticking have been
computed for a number of configurations involving adsorption on top of carbon
atoms. We find that binding energies per atom range from ~0.8 eV to ~1.9 eV,
with barriers to sticking in the range 0.0-0.2 eV. In addition, depending on
the number and location of adsorbed hydrogen atoms, we find that magnetic
structures may form in which spin density localizes on a
$\sqrt{3}{x}\sqrt{3}{R}30^{\circ}$ sublattice, and that binding (barrier)
energies for sequential adsorption increase (decrease) linearly with the
site-integrated magnetization. These results can be rationalized with the help
of the valence-bond resonance theory of planar $\pi$ conjugated systems, and
suggest that preferential sticking due to barrierless adsorption is limited to
formation of hydrogen pairs.

35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio