  The insulator to metal transition in LaTiO_3 induced by La substitution via
Sr is studied within multi-band exact diagonalization dynamical mean field
theory at finite temperatures. It is shown that weak hole doping triggers a
large interorbital charge transfer, with simultaneous electron and hole doping
of t2g subbands. The transition is first-order and exhibits phase separation
between insulator and metal. In the metallic phase, subband compressibilities
become very large and have opposite signs. Electron doping gives rise to an
interorbital charge flow in the same direction as hole doping. These results
can be understood in terms of a strong orbital depolarization.
