  We investigate the occurrence of multicritical points under pressure and
magnetic field in a model that describes two 5f bands (of either $\alpha$ or
$\beta$ characters) which hybridize with a single itinerant conduction band.
The 5f-electrons interact through Coulomb and exchange terms. The AF order
parameter is a N\'eel vector, which is assumed to be fixed by an Ising
anisotropy. The applied magnetic field is transverse to the anisotropy axis.
Without field, our results for the temperature - pressure phase diagram show
that, at low temperatures, a first-order phase transition occurs between two
distinct antiferromagnetic phases, AF$_1$ and AF$_2$, as the pressure is
increased. The two phases are characterized by the gaps of bands $\alpha$ and
$\beta$ given by $\Delta_{\alpha}$ and $\Delta_{\beta}$, respectively. The
AF$_1$ phase occurs when $\Delta_{\beta}>\Delta_{\alpha}>0$, while in the
AF$_2$ phase, the gaps satisfy $\Delta_{\alpha}>\Delta_{\beta}>0$. The
application of a magnetic field produces a drastic change in the phase diagram.
The AF1 and AF2 phases separate with the latter acquiring a dome shape which is
eventually suppressed for large values of the applied field. The evolution of
the phase diagram under pressure, without and with magnetic field, shows the
presence of multicritical points. Our results show that the evolution of these
multicritical points by the simultaneous application of pressure and field is
also drastic with the suppression of some multicritical points and the
emergence of others ones. We believe that these results may have relevance for
the growing field of multicritical points (classical and quantum) in the
physics of Uranium compounds.
