  Preliminary results of numerical simulations of electron and positron
channeling and emission spectra are reported for straight, uniformly bent and
periodically bent silicon crystal. The projectile trajectories are computed
using the newly developed module [1] of the MBN Explorer package [2,3]. The
electron and positron channeling along Si(110) and Si(111) crystallographic
planes are studied for the projectile energies 195--855 MeV.
