  Motivated by the recent report of broken time-reversal symmetry and zero
momentum magnetic scattering in underdoped cuprates, we investigate under which
circumstances orbital currents circulating inside a unit cell might be
stabilized in extended Hubbard models that explicitly include oxygen orbitals.
Using Gutzwiller projected variational wave functions that treat on an equal
footing all instabilities, we show that orbital currents indeed develop on
finite clusters, and that they are stabilized in the thermodynamic limit if
additional interactions, e.g. strong hybridization with apical oxygens, are
included in the model.
