Correlated Topological Insulators with Mixed Valence
  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. 
Feng Lu, JianZhou Zhao, Hongming Weng, Zhong Fang and Xi Dai
cond-mat.str-el