Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Born Effective Charges and Infrared Response of LiBC   Calculations of the zone center optical mode frequencies (including LO-TO
splitting), Born effective charges Z$^*_{\alpha\alpha}$ for each atom,
dielectric constants $\epsilon_{0}$ and $\epsilon_{\infty}$, and the dielectric
response in the infrared, using density functional linear response theory, are
reported. Calculated Raman modes are in excellent agreement with experimental
values (170 cm$^{-1}$ and 1170 cm$^{-1}$), while it will require better
experimental data to clarify the infrared active mode frequencies. The Born
effective charges Z$^*_{\alpha \alpha}$ (i) have surprisingly different values
for B and C, and (ii) show considerable anisotropy. Relationships between the
effective charges and LO-TO splitting are discussed, and the predicted
reflectivity in the range 0 -- 1400 cm$^{-1}$ is presented. These results hold
possible implications for Li removal in LiBC, and C substition for B in
MgB$_2$.

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The categories of this paper are: math-ph
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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci
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The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
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The categories of this paper are: funct-an
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: stat