A possible scenario of metallization in boron doped diamond CB$_x$
  Possibility for collectivization of acceptor states in a semiconductor, converting it to metal, is discussed within the scope of Anderson s-d hybride model. This model is generalized for multicomponent band structure and composite acceptor states, localized on pairs of neighbor dopants (impurity "dumbbells"), in order to describe boron doped diamond CB$_x$. The resulting parameters of band structure, in particular, position of the Fermi level, are compared to the recent experimental data on metallized and superconducting CB$_x$. 
Yu.G. Pogorelov and V.M. Loktev