Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Face-Centered-Cubic B$_{80}$ Metal: Density functional theory
  calculations   By means of ab initio calculations within the density functional theory, we
have found that B80 fullerenes can condense to form stable face-centered-cubic
fcc solids. It is shown that when forming a crystal, B80 cages are
geometrically distorted, the Ih symmetry is lowered to Th, and four boron-boron
chemical bonds are formed between every two nearest neighbor B80 cages. The
cohesive energy of B80 fcc solid is 0.23 eV/atom with respect to the isolated
B80 fullerene. The calculated electronic structure reveals that the fcc B80
solid is a metal. The predicted solid phase would constitute a form of pure
boron and might have diverse implications. In addition, a simple electron
counting rule is proposed, which could explain the stability of B80 fullerene
and the recently predicted stable boron sheet.

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The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc