Abstract:
It is shown that the potential of oscillating lattice at fixed moment of time is a quasi-periodical function. Stationary states of quantum particle in quasi-periodical
potential satisfy the generalized Floquet–Bloch theorem and can be characterized by
the quasi-momentum which is connected with the density of states exactly in the same
way as in the case of the particle in a purely periodical potential. If the quasi-momentum
satisfies the generalized Bragg–Woolfe conditions, the spectrum may include
the lacunae (forbidden zones), for the sizes of which the estimates are given.