  We examine critical properties of the quarter-filled one-dimensional Hubbard
model with dimerization and with the onsite and nearest-neighbor Coulomb
repulsion U and V. By utilizing the bosonization method, it is shown that the
system exhibits an Ising quantum phase transition from the Mott insulating
state to the charge-ordered insulating state. It is also shown that the
dielectric permittivity exhibits a strong enhancement as decreasing temperature
with power-law dependence at the Ising critical point.
