The second part of this work examines a number of applications of the theory.
We present a new microscopic derivation of the intervalley deformation
potentials within the tight binding representation and computes a number
of conduction-band deformation potentials of bulk semiconductors. We have
also studied the electronic states in heterostructures and have shown theoretically
the possibility of having barrier localization of above-barrier states
in a multivalley heterostructure using a multiband calculation. Another
result is the proposal for a new "type-II" lasing mechanism in
short-period GaAs/AlAs superlattices. As for our work on the optical properties,
a new formalism, based on the generalized Feynman-Hellmann theorem, for
computing interband optical matrix elements has been obtained and has been
used to compute the linear and second-order nonlinear optical properties
of a number of bulk semiconductors and semiconductor heterostructures.
In agreement with the one-band elective mass calculations of other groups,
our more elaborate calculations show that the intersubband oscillator strengths
of quantum wells can be greatly enhanced over the bulk interband values.