  In this paper we investigate the completeness of the Stark resonant
eigenstates for a particle in a square-well potential. We find that the
resonant state expansions for target functions converge inside the potential
well and that the existence of this convergence does not depend on the depth of
the potential well. By analyzing the asymptotic form of the terms in these
expansions we prove some results on the relation between smoothness of target
functions and the rate of convergence of the corresponding resonant state
expansion.
