The structure of the ground state of the quantum discrete Frenkel-Kontorova
model was numerically analyzed by means of the Metropolis algorithm
in [38,41]. Special attention was given to the effects of quantization on the
Cantori structure of the classical ground state. It was shown that these
quantum effects produce a new structure which is described by using a sawtooth
map instead of the Chirikov standard map. At sufficiently large values
of 
the Cantori is destroyed. These results formed the basis of thesis
of F.Borgonovi (Pavia Univ., 1990).