Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Atomic structure and vibrational properties of icosahedral B$_4$C boron
  carbide   The atomic structure of icosahedral B$_4$C boron carbide is determined by
comparing existing infra-red absorption and Raman diffusion measurements with
the predictions of accurate {\it ab initio} lattice-dynamical calculations
performed for different structural models. This allows us to unambiguously
determine the location of the carbon atom within the boron icosahedron, a task
presently beyond X-ray and neutron diffraction ability. By examining the inter-
and intra-icosahedral contributions to the stiffness we show that, contrary to
recent conjectures, intra-icosahedral bonds are harder.

8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio