A multi-scale approach to computational photonics

A combination of ab initio methods to simulate the atomic structure of solids with numerical methods to simulate complex dielectric materials allows for a proper modeling of photonic devices. This approach provides useful information on the atomic scale as well as on the mesoscopic or macroscopic scale of the resulting devices. We discuss the basic features of this multi-scale approach, focusing on first principles dielectric properties based on Density Functional Theory (DFT), and we give some illustrative examples.