Wavevector-dependent optical properties from wavevector-independent proper conductivity tensorRonald Starke, René Wirnata, Giulio A.H. Schober, Nebahat Bulut and Jens KortusEur. Phys. J. B, 93 3 (2020) 54DOI: https://doi.org/10.1140/epjb/e2019-90569-0