  The ground state of a one-dimensional Hubbard model with a bond-charge
attraction W term at half-filling is investigated by the density matrix
renormalization group method. It is confirmed that the spin gap will be closed
at U>8W. But the long-range bond order wave survives even when the spin gap is
closed. It indicates that the ground state is a novel dimerized spin fluid at
U>8W. By a charge-spin transformation, it is shown that there should be a
dimerized metallic phase at U<-8W. Furthermore, it is found that the Hubbard
interaction U enhances initially the dimerization for a weak bond charge
attraction W whereas it reduces monotonously the dimerization for a stronger
bond charge attraction W.
