On the correllation effect in Peierls-Hubbard chains

We reexamine the dimerization, the charge and the spin gaps of a half-filled Peierls-Hubbard chain by means of the incremental expansion technique. Our numerical findings are in significant quantitative conflict with recently obtained results by M. Sugiura and Y. Suzumura [J. Phys. Soc. Jpn. v. 71 (2002) 697] based on a bosonization and a renormalization group method, especially with respect to the charge gap. Their approach seems to be valid only in the weakly correlated case.