Dielectric function in semi-empirical tight-binding theory applied to crystalline diamond

A semi-empirical tight-binding theory is employed to calculate the electronic band structure and the imaginary part of the dielectric function of crystalline diamond. Also, in order to validate the parameters used in this work, we have performed calculation by means of density functional theory with the local density approximation theory. We present the dependence of the dielectric function on the photon energy within two different approaches: interatomic and intra-atomic momentum matrix elements, which are applied and compared.