Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Density functional theory study of vacancy induced magnetism in
  Li$_{3}$N   The effect of lithium vacancies in the hexagonal structure of
$\alpha-$Li$_3$N, is studied within the framework of density functional theory.
Vacancies ($\square$) substituting for lithium in
$\alpha-$Li$_2$(Li$_{1-x}\square_x$)N are treated within the coherent potential
approximation as alloy components. According to our results long range
N($p$)-ferromagnetism ($\sim 1$ $\mu_B$) sets in for vacancy substitution
within the [Li$_2$N] layers ($x \ge 0.7$) with no significant change in unit
cell dimensions. By total energies differences we established that in-plane
exchange couplings are dominant. Vacancies substituting inter-plane Li, leads
to a considerable structural collapse ($c/a \approx 0.7$) and no magnetic
moment formation.

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The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
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The categories of this paper are: dg-ga
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: q-fin
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The categories of this paper are: stat