  The quasi-channeling of positive and negative relativistic particles in a
bent crystal is studied using the classical deflection function. It was shown
that the potential scattering in a central field of bounded ring-like
potentials may produce the ``reflected'' and ``refracted'' fractions of
scattered particles. For particles with positive charge the ``reflected''
fraction is mainly presented; at the same time we predict that for particles
with negative charge the ``refracted'' fraction should dominate. The effect of
``empty core'' for central scattering is also discussed. The average deflection
angles for volume ``reflection'' and ``refraction'' are derived for accepted
potential model of the crystal. The calculated average ``reflection'' angle is
in satisfactory agreement with recent experimental data \cite{ivanov_2006}
