  Equations for the electron Green's function of the two-dimensional Hubbard
model, derived using the strong coupling diagram technique, are
self-consistently solved for different electron concentrations $n$ and
tight-binding dispersions. Comparison of spectral functions calculated for the
ratio of Hubbard repulsion to the nearest neighbor hopping $U/t=8$ with Monte
Carlo data shows not only qualitative, but in some cases quantitative agreement
in position of maxima. General spectral shapes, their evolution with momentum
and filling in the wide range $0.7\lesssim n\leq 1$ are also similar. At
half-filling and for the next nearest neighbor hopping constant $t'=-0.3t$ the
Mott transition occurs at $U_c\approx 7\Delta/8$, where $\Delta$ is the initial
bandwidth. This value is close to those obtained in the cases of the
semi-elliptical density of states and for $t'=0$. In the case $U=8t$ and
$t'=-0.3t$ the Mott gap reaches maximum width at $n=1.04$, and it is larger
than that at $t'=0$ for half-filling. In all considered cases positions of
spectral maxima are close to those in the Hubbard-I approximation.
