  The Peierl's tight-binding model, with the band Hamiltonian matrix, is used
to calculate the magnetoelectronic structure of a monolayergraphite. There are
many flat Landau levels and some oscillatory Landau levels. The low
Landau-level energies are characterized by a simple relation, not for others.
State degeneracy is, respectively, fourfold degenerate and doubly degenerate at
low and high energies. The level spacing declines quickly and then grows
gradually in the increase of state energy. The main features of electronic
properties are directly reflected in density of states. The predicted results
could be verified by the optical spectroscopy.
