ELECTRONIC STATES IN DISORDERED SYSTEMS

Abstract

The work reported in this thesis is some of the author's attempts to understand the behaviour of electrons in disordered systems. The subject dealt here is a part of the extensively growing field of noncrystalline or aperiodic systems, in which enough stimuli have been created to understand the phenomena of disorder in the recent years. Because of the great progress in the experi-mental techniques, yielding reliable (experimental) results in the disordered materials like metallic binary alloys, impure semiconductors, liquid metals and glasses around 1960, theoretical attempts were made to understand better,the problem of elementary excitations in dis-ordered systems. One of the landmarks is the Andersoris classic paper "On the absence of diffusion in certain random lattice" and this was followed by discusSions due to Mott, Ziman, Thoulesa- and others regarding the nature of the wave functions of electrons in systems having random potentials. The usual tools of band theory, were not applicable to such systems where translational symmetry is incomplete or absent. Due to the impetus gained by rapid advancements of computer technology, refinement and ingenuity of experimental methods, many sophisticated techniques like Green function approach are developed to solve the problem of electrons in disordered systems.