The Generalized Gutzwiller Method for n=>2 Correlated Bands: First Order   Metal-Insulator Transitions
  We have generalized the Gutzwiller method to the cases of n=>2 correlated bands and report studies on a degenerate two-band model with Hund's rule type on-site interactions. At half band filling the metal-insulator transitions are usually of first order. 
J. Buenemann and W. Weber