Aspects of the normal state phase of copper oxide planes in high Tc superconductors

We examine various aspects of the normal state phase of ${\rm CuO_{2}}$ planes in the high Tc superconductors. In particular, within the context of the three band Hubbard model, we study as a function of doping the competition between a charge density wave phase induced by oxygen breathing modes, antiferromagnetic order and paramagnetism. To account for the strong electronic interactions, we use the finite $U$ slave boson method of Kotliar and Ruckenstein.