Eigenfunctions of the Inverse Dielectric Functions and Response Functions of Silicon and Argon

The inverse dielectric function and response function are key quantities in the dielectric response of materials. The Hermitian, inverse dielectric function can be diagonalised to yield the dielectric band structure (DBS) and a set of eigenpotentials for a crystalline solid. The response function can also be diagonalised to yield a set of eigenfunctions which are similar in character to the eigenpotentials for the solid. The DBS and response functions of argon and silicon are calculated and analysed. The most important eigenpotentials of solid argon and silicon are atom-centred monopolar and dipolar functions for argon and atom-centred monopolar and dipolar functions and bond-centred dipolar functions for silicon. These ab initio calculations provide insight into the success of discrete dipole models for optical properties of semiconductor surfaces.