Calculation of the electronic structure of disordered systems by a new technique

V ABSTRACT Ph.D THESIS CALCULATION OF THE ELECTRONIC STRUCTURE OF DISORDERED SYSTEMS BY A NEW TECHNIQUE Cengiz TATAR Firat University Graduate school of Science and Technology Department of Physics 2002, Page :77 In this study, a method based on multiple scattering theory is introduced for calculating the electronic structure of disordered systems. The method, of which theory was developed by Beeby, is defined within two versions for the purpose of applying to both structurally disordered and substitutional disordered systems. The version defined for structurally disordered systems called Beeby-Hayes method is applied to a model known as diced lattice, which is a kind of structural disordered, and the density of states is calculated. In this calculation, the variation of the density of states of the model to the concentration values of 3-fold and 6-fold lattices is investigated. It was found that the density of states forms with respect to the values of the concentrations The second version applied to substitutional disordered systems is a self- consistent one introduced as Beeby method. The method is first applied to basic cubic, face centre cubic and body centre cubic lattices and their electronic density of states are calculated. The results are in agreement perfectly with the literature. Then, the density of states is investigated to the concentrations of two and three components distributed randomly on these lattices. It has been obtained that the densities of states appear at their bound state energies defined for each component. Moreover, it has also been obtained that the density of states varies with respect to the ratio of bandwidth (W) to bound state energies (AE), (W/AE). Keywords: Electronic Density of States, Structural disordered systems, Substitutional Disordered, Multiple Scattering Theory.