  There exists presently considerable debate over the question whether local
Coulomb interactions can explain the absence of the small e'_g Fermi surface
hole pockets in photoemission studies of Na_{0.3}CoO_2. By comparing dynamical
mean field results for different single particle Hamiltonians and exact
diagonalization as well as quantum Monte Carlo treatments, we show that, for
realistic values of the Coulomb energy U and Hund exchange J, the e'_g pockets
can be slightly enhanced or reduced compared to band structure predictions, but
they do not disappear.
