LayerOptics: Microscopic modeling of optical coefficients in layered materials

摘要

Theoretical spectroscopy is a powerful tool to describe and predict opticalproperties of materials. While nowadays routinely performed, first-principlescalculations only provide bulk dielectric tensors in Cartesian coordinates.These outputs are hardly comparable with experimental data, which are typicallygiven by macroscopic quantities, crucially depending on the laboratory setup.Even more serious discrepancies can arise for anisotropic materials, e.g.,organic crystals, where off-diagonal elements of the dielectric tensor cansignificantly contribute to the spectral features. Here, we presentLayerOptics, a versatile and user-friendly implementation, based on thesolution of the Maxwell's equations for anisotropic materials, to computeoptical coefficients in anisotropic layered materials. We apply this tool forpost-processing full dielectric tensors of molecular materials, includingexcitonic effects, as computed from many-body perturbation theory using theexciting code. For prototypical examples, ranging from optical to X-rayfrequencies, we show the importance of combining accurate ab initio methods toobtain dielectric tensors, with the solution of the Maxwell's equations tocompute optical coefficients accounting for optical anisotropy of layeredsystems. Good agreement with experimental data supports the potential of ourapproach, in view of achieving microscopic understanding of spectroscopicproperties in complex materials.