  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.
