  We consider the stationary solutions for a class of Schrodinger equations
with a N-well potential and a nonlinear perturbation. By means of semiclassical
techniques we prove that the dominant term of the ground state solutions is
described by a N-dimensional Hamiltonian system, where the coupling term among
the coordinates is a tridiagonal Toeplitz matrix. In particular we consider the
case of N=4 wells, where we show the occurrence of spontaneous
symmetry-breaking bifurcation effect. In particular, in the limit of large
focusing nonlinearity we prove that the ground state stationary solutions
consist of N wavefunctions localized on a single well.
