In a Physical Review B paper Chandross and Hicks claim that an analysis of
the density-density correlation function in the dimerised Hubbard model of
polyacetylene indicates that the optical exciton is bound, and that a previous
study by Boman and Bursill that concluded otherwise was incorrect due to
numerical innacuracy. We show that the method used in our original paper was
numerically sound and well established in the literature. We also show that,
when the scaling with lattice size is analysed, the interpretation of the
density-density correlation function adopted by Chandross and Hicks in fact
implies that the optical exciton is unbound.Comment: RevTeX, 10 pages, 4 eps figures fixed and included now in tex