  The non-uniform ground state of the two-dimensional three-band Hubbard model
for the oxide high-Tc superconductors is investigated using a variational Monte
Carlo method. We examine the effect produced by holes doped into the
antiferromagnetic (AF) background in the underdoped region. It is shown that
the AF state with spin modulations and stripes is stabilized du to holes
travelling in the CuO plane. The structures of the modulated AF spins are
dependent upon the parameters used in the model. The effect of the boundary
conditions is reduced for larger systems. We show that there is a region where
incommensurability is proportional to the hole density. Our results give a
consistent description of stripes observed by the neutron- scattering
experiments based on the three-band model for CuO plane.
