Exciton theory in amorphous materials

In the present paper a second quantization formalism is used to derive a general expression for the exciton hamiltonian in disordered materials. It is shown how exciton creation and annihilation operators, acting as bosons, can be introduced. The exciton hamiltonian is diagonalized by an appropriate transformation for the exciton operators. We furthermore introduced the concept of the electronic polarization due to an exciton. The polarization coefficients are calculated by a simple variational technique. An appropriate configurational average of the results is taken, in order to eliminate the position vectors of the different constituent atoms.