  We report density functional theory calculations for the parent compound
LaOFeAs of the newly discovered 26K Fe-based superconductor
LaO$_{1-x}$F$_x$FeAs. We find that the ground state is an ordered
antiferromagnet, with staggered moment about 2.3$\mu_B$, on the border with the
Mott insulating state. We fit the bands crossing the Fermi surface, derived
from Fe and As, to a tight-binding Hamiltonian using maximally localized
Wannier functions on Fe 3d and As 4p orbitals. The model Hamiltonian accurately
describes the Fermi surface obtained via first-principles calculations. Due to
the evident proximity of superconductivity to antiferromagnetism and the Mott
transition, we suggest that the system may be an analog of the electron doped
cuprates, where antiferromagnetism and superconductivity coexist.
