  We propose the local density approximation (LDA)+Gutzwiller method
incorporating Green's function scheme to study the topological physics of
correlated materials from the first-principles. Applying this method to typical
mixed valence materials SmB6, we found its non-trivial Z2 topology, indicating
that SmB6 is a strongly correlated topological insulator (TI). The unique
feature of this compound is that its surface states contain three Dirac cones
in contrast to most known TIs.
