Quantum phase transitions in one-dimensional Peierls-Hubbard model with next-nearest-neighbor hopping integrals

Two kinds of phase transitions observed in the half-filled Peierls-Hubbard chain with the next-nearest-neighbor hopping integral are investigated. In the uniform case, according to the conformal field theory prediction, we numerically determine a phase boundary between the spin-fluid and dimer states. Then, the criticality of the spin-Peierls transition (i.e.; power-law dependences of the energy gain and spin gap on the lattice dimerization parameter) is argued on the phase boundary.