  We show that the numerical results contained in a recent paper are affected
by a non optimal implementation of the methods which have been used to obtain
these results. A careful analysis done using the Rayleigh-Ritz method provides
a rigorous upper bound for the energy of the ground state of an electron in a
two dimensional potential generated by the edge dislocation, as well as precise
values for the excited states. The extrapolation of the results corresponding
to different subspaces is used to obtain a precise estimate of the fundamental
energy of the model. The energies of the first 500 states that we have
calculated are in perfect agreement with the expected asymptotic behavior.
