Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bright $\mathrm{\textit{ab-initio}}$ photoluminescence of NV+ in diamond   The positively charged nitrogen vacancy (NV+) centre in diamond has been
traditionally treated as a dark state due to the experimental lack of an
optical signature. Recent computational studies have shown that it is possible
for the NV+ defect to have an excited state transition equivalent to that of
the negatively charged (NV-) centre, but no PL predictions have been reported
so far. We report the first $\mathrm{\textit{ab-initio}}$ calculation showing
that the NV+ center presents quantum emission, with zero phonon line at 765 nm
and a non-zero transition dipole moment, approximately 4x smaller than the
transition dipole moment of NV-. We calculate the energy levels of the
multielectron states under time-dependent density functional theory (singlet
and triplet E states), and using our recently developed frequency cutoff
method, we predict the full PL spectrum. Our results suggest that this state
cannot be considered intrinsically 'dark' and charge specific quenching
mechanisms should be investigated as the cause of the lack of optical activity
in experimental characterizations.

28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas