Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ab initio Study of Nonlinear Optical Susceptibilities in Silicon
  Nanowires   Using Time Independent Density Functional Theory (TIDFT) it is shown that the
2nd order optical susceptibilities of narrow (1nm-2nm) Silicon Nanowires (SiNW)
are enhanced due to surface termination. The value of $\chi^{(2)}$ is enhanced
up to 200 pm/V which is promising a strong Second Harmonic Generation (SHG) in
SiNWs. For [100], [110] and [111] SiNWs, yxx component of $\chi^{(2)}$ tensor
is 81, 225 and 81 pm/V, respectively. These are in close agreement with
$\chi^{(2)}$ values reported for strained silicon waveguides in experiments.
The 3rd order susceptibility, $\chi^{(3)}$, is within the range of
(0.1-12)x$10^{-18} \frac{m^{2}}{V^{2}}$ which is close to the experimental
values of bulk silicon (0.1-0.2)x$10^{-18} \frac{m^{2}}{V^{2}}$ for [110] and
[100] SiNWs and it is 100 times better for [111] SiNW. This study suggests
possibilities of enhancing SHG in SiNWs through symmetry breaking via strain
and surface termination/reconstruction as well as suitability of this DFT-based
method in predicting nonlinear optical susceptibilities of nano structures.

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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph
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The categories of this paper are: nlin
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The categories of this paper are: eess
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The categories of this paper are: astro-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: ao-sci
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The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
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The categories of this paper are: stat