  It is demonstrated that the signatures of the Hubbard Model in the strongly
interacting regime can be simulated by modifying the screening in the limit of
zero wavevector in Projector-Augmented Wave GW calculations for systems without
significant nesting. This modification, when applied to the Mott insulator CuO,
results in the opening of the Mott gap by the splitting of states at the Fermi
level into upper and lower Hubbard bands, and exhibits a giant transfer of
spectral weight upon electron doping. The method is also employed to clearly
illustrate that the M$_{1}$ and M$_{2}$ forms of vanadium dioxide are
fundamentally different types of insulator. Standard GW calculations are
sufficient to open a gap in M$_{1}$ VO$_{2}$, which arise from the Peierls
pairings filling the valence band, creating homopolar bonds. The valence band
wavefunctions are stabilized with respect to the conduction band, reducing
polarizability and pushing the conduction band eigenvalues to higher energy.
The M$_{2}$ structure however opens a gap from strong on-site interactions; it
is a Mott insulator.
