  In this paper, we consider the Frenkel-Kontorova model of a one dimensional
chain of atoms submitted to a potential. This potential splits into an
interaction potential and a potential induced by an underlying substrate which
is a quasicrystal. Under standard hypotheses, we show that every minimal
configuration has a rotation number, that the rotation number varies
continuously with the minimal configuration, and that every non negative real
number is the rotation number of a minimal configuration. This generalizes well
known results obtained by S. Aubry and P.Y. le Daeron in the case of a
crystalline substrate.
