Electrical Conductivity of Bond-Type Disordered Systems —Effect of Fluctuation of Transfer Energies—

The theory for the electrical conductivity of bond-type disordered systems is formulated in the single-bond coherent-potential approximation and applied to calculate the conductivity of some model systems as functions of the energy and the degree of disorder. The results are discussed in connection with the electron localization problems such as the bond percolation problem and the Anderson localization problem with fluctuatuon of transfer energies.