The motion of relativistic particles in crystals is complicated. At certain crystal orientations with respect to an electron
beam, the motion of particles may become either regular (periodic) or chaotic. A regular type of electron motion results
in interfering the emitted radiation due to periodical collisions of electrons with the atomic strings. In this case, sharp
maxima appear in photon radiation spectra. Existence of periodical electron motion may result in high polarization of the
radiation. For particles with an irregular type of the motion, periodicity of the atomic strings does not have any essential
influence to radiation characteristics, and, hence, dynamic chaos phenomenon will take place. Subsequently, interference
of radiation, due to electron scattering by single strings, disappears, and the radiation spectra have no sharp maxima;
however, intensity of such radiation is significantly higher than radiation intensity in amorphous matter. The radiation
spectra and polarization are very sensitive to the type of particle motion in a crystal, and depend on initial energy of
particles. At electron energies of about a few hundred MeV the coherent effects of radiation in crystals are not
sufficiently investigated. In this report the expected radiation characteristics (spectra and polarization) are presented for
these electron energies, and possibilities of its experimental investigation at the SPARC facility (Frascati) are considered.
Possibilities for experimental studying the dynamic chaos phenomena at electron motion in a crystal are discussed.