Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theory and MD simulations of intrinsic localized modes and defect
  formation in solids   MD simulations of recoil processes following the scattering of X-rays or
neutrons have been performed in ionic crystals and metals. At small energies
(<10 eV) the recoil can induce intrinsic localized modes (ILMs) and linear
local modes associated with them. As a rule, the frequencies of such modes are
located in the gaps of the phonon spectrum. However, in metallic Ni, Nb and Fe,
due to the renormalization of atomic interactions by free electrons, the
frequencies mentioned are found to be positioned above the phonon spectrum. It
has been shown that these ILMs are highly mobile and can efficiently transfer a
concentrated vibrational energy to large distances along crystallographic
directions. If the recoil energy exceeds tens of eVs, vacancies and
interstitials can be formed, being strongly dependent on the direction of the
recoil momentum. In NaCl-type lattices the recoil in (110) direction can
produce a vacancy and a crowdion, while in the case of a recoil in (100) and in
(111) directions a bi-vacancy and a crowdion can be formed.

34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
10
The categories of this paper are: q-bio