POSITION-DEPENDENT EFFECTIVE-MASS AND GALILEAN INVARIANCE

Instantaneous Galilean invariance is used to derive from first princip les the expression for the Hamiltonian of an electron with a position- dependent effective mass, as well as the adequate boundary conditions for the wave function in the case of abrupt heterojunctions. A very el ementary model sustaining these results in the envelope-function appro ximation is also proposed.