  We discuss the first theory for the depinning of low dimensional,
incommensurate, charge density waves (CDWs) in the strong electron-phonon (e-p)
regime. Arguing that most real CDWs systems invariably develop a gigantic
dielectric constant (GDC) at very low frequencies, we propose an
electromechanical mechanism which is based on a local field effect. At zero
electric field and large enough e-p coupling the structures are naturally
pinned by the lattice due to its discreteness, and develop modulation functions
which are characterized by discontinuities. When the electric field is turned
on, we show that it exists a finite threshold value for the electric field
above which the discontinuities of the modulation functions vanish due to CDW
deformation. The CDW is then free to move. The signature of this
pinning/depinning transition as a function of the increasing electric field can
be directly observed in the phonon spectrum by using inelastic neutrons or
X-rays experiments.
