  Motivated by the controversy between quantum chemists and solid-state
physicists, and by recent experimental results, spin-polarized
density-functional (DFT) calculations are used to probe electron correlation in
the Si(100) reconstructed surface. The ground state displays antiferromagnetic
spin polarization for low dimer inclinations indicating, not magnetic order,
but the importance of Mott-like correlations among dangling bonds. The lowest
energy corresponds to a higher dimer inclination with no spin. DFT energies,
however, should be taken with caution here. Our results together with
quantum-chemical findings suggest dimers with highly correlated electrons that
tend to buckle due to interactions with other dimers.
