Local electric field investigation of Si 2N 2O and its electronic structure, elastic and optical properties

Abstract

This paper demonstrates that the Clausius–Mosotti equation cannot be used for Si 2N 2O since the Lorenz approximation is invalid therein. Therefore a modified definition for the Lorenz electric field is suggested which can be derived from the optical dielectric constant calculated using the plane-wave pseudopotential method. In addition, other parameters of Si 2N 2O such as the energy band gap, density of states, elastic and optical properties are also given in this paper. Based on the new expression for local electric field, the modified Clausius–Mosotti equation is suggested, and then the dielectric constant of Si 2N 2O is discussed by using the additivity rule. It is found that the result of the phenomenological analysis of the dielectric constant is basically consistent with the experimental data and the first principles results, which explain the experimental observation that the dielectric constant of Si 2N 2O is enhanced with the increase of Li content. Also, the modified Clausius–Mosotti equation and the additivity rule are suggested to be used in predicting the dielectric behaviors of the new and complex compounds.