  This article is devoted to the numerical study of the existence of the
eigenvalues of the Hamiltonian describing a quantum particle living on three
dimensional straight strip of width $d$ in the presence of an electric field of
constant intensity $F$ in the direction perpendicular to the electron plane. We
impose Neumann boundary conditions on a disc window of radius $a$ and Dirichlet
boundary conditions on the remaining part of the boundary of the strip.
