Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Zn-related deep centers in wurtzite GaN   Zn in GaN forms an efficient radiative center and acts as a deep acceptor
which can make the crystal insulating. Four different Zn-related centers have
been by now identified, leading to light emission in the range between 1.8 eV
and 2.9 eV. We present a first-principles investigation total energy and
electronic structure calculations for Ga-substitutional and hetero-antisite
N-substitutional Zn in wurtzite GaN, using ultrasoft pseudopotentials and a
conjugate-gradient total energy minimization method. Our results permit the
identification of the blue-light emission center as the substitutional
acceptor, while contrary to a common belief the Zn_N heteroantisite has a very
high formation energy and donor behavior, which seems to exclude it as the
origin of the other centers.

9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph