Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Computational investigation on non-linear optical properties of
  hexaphyrin and core modified hexaphyrins   Expanded porphyrin-based (Hexaphyrins) sensitizers are promising due to their
excellent light harvesting feature in dye-sensitized solar cell (DSSC). We
calculated the low-lying excitations of expanded porphyrins (EPs) as hexaphyrin
and core modified hexaphyrin structures using Time-Dependent Density Functional
Theory. Our calculation showed the EPs (both hexaphyrin and core modified
hexaphyrin) have broad range of absorption band suitable for harvesting the
visible and near infrared region of solar spectrum. All EPs studied here
satisfy the energy condition of singlet fission (SF). SF is the process in
which the theoretical limit of Shockley-Quiesser (SQ) (33\%) can be overcome in
single junction solar cell. The non-linear optical properties like first hyper
polarizability $\beta$ and second order hyper polarizability $\gamma$ were
calculated using coupled perturbed Hartree-Fock approach. From the second order
NLO properties we carried out degenerate four wave mixing (DFWM) component
($\gamma^{(2)}(-\omega;\omega,\omega,-\omega$)) and finally quadratic non
linear refractive indices of these EPs are calculated. Calculation showed EPs
are promising as organic dye for the opto-electronic applications and useful
for high efficiency DSSC and also useful for potential NLO materials as their
hyper polarizabilities showed higher order non linearities.

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The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
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The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
1
The categories of this paper are: cs