Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First-Principles Study of Structural and Electronic Properties of
  Germanene   The ground state structural and electronic properties of germanene (the
germanium analogue of graphene) are investigated using first-principles
calculations. On structure optimization, the graphene-like honeycomb structure
of germanene turns out as buckled (buckling parameter $\Delta = 0.635$ \AA) in
contrast with graphene's planar structure (buckling parameter $\Delta = 0.0$
\AA). In spite of this, germanene has similar electronic structure as that of
graphene. While corroborating the reported results, we newly predict the
in-plane contraction of hexagonal Ge with (thermal) stretching along the "c"
axis, akin to a phenomenon observed in graphite.

37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat