Dielectric matrices in semiconductors: A direct approach

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Abstract
A new method for the evaluation of dielectric screening matrices in semiconductors is proposed. The present method is direct, in the sense that it avoids the use of slowly convergent perturbation sums, just by treating the crystal with a built-in perturbation as a new system. The several advantages of this approach with respect to previous ones are discussed. As a first application of the method, we calculate the random-phase approximation (RPA) dielectric matrices of Si and GaAs at the Γ, X, and L points; the results show the effectiveness and accuracy of the method. The possibility of extending beyond RPA is also discussed.