Computer study of the dependence of the d-electronic structure of amorphous systems on their atomic structure

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Abstract
Computer modelling of the atomic structure of real amorphous systems meets the serious problem of our vague information about the effective interatomic interactions. The uncertainty about the atomic structure is projected into the results of the electronic structure calculations. Here the sensitivity of the d-electronic structure of an amorphous system to various parameters of the structural model is investigated. The dependence on the size of the structural model of the density of d-electronic states (DOS), the effect on the resulting DOS of the periodic boundary conditions, the dependence of DOS on the thermodynamic state of the system (temperature, density) and on the parameters of the Morse interatomic potential used in the structural simulation are examined. Particular attention is paid to the dependence on atomic configurations of the d-electronic structure. The structural models were generated by means of thermodynamic simulation methods. The electronic structure was calculated by the recursion method. A model of 256 atoms with a periodic boundary condition appears to be sufficiently large to provide the basic features of the d-electronic structure of an amorphous system. The shape of the DOS curve is most sensitive to those parameters of the structural model which affect the interatomic distances and the local arrangement of the atoms, and in particular to the repulsive part of the interatomic potential. The configuration fluctuations of the total-one-electron energy of the 256-atom model of an amorphous system at 300 K are less than 0.01%.