Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nesting properties and anomalous band effect in MgB2   First principle FLAPW band calculations of the new superconductor MgB2 were
performed and the polarization function P12(Q) between the two p-bands mainly
formed of boron pz-orbital was calculated. We found that P12(Q) is
substantially enhanced around Q=(0,0,p/c), which supports the two-band
mechanism of superconductivity for MgB2. P12(Q) peaks at Qz ~ 0.3(2p/c) and Qz
\~ 0.5(2p/c). These two peaks are related to the nesting of these Fermi
surfaces, but significantly deviates from the position expected from the
simplest tight-binding bands for the p-bands. From the calculations for
different lattice parameters, we have found significant dependences on the
isotopic species of B and on the pressure effect of the polarization function
in accordance with the respective changes of Tc in the above-mentioned
framework.

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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: econ
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The categories of this paper are: stat
1
The categories of this paper are: cs
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: nlin