Figure 4

Spatially average (a) imaginary (Im \(\varepsilon\)) and (b) real (Re \(\varepsilon\)) part of the dielectric function for (un)doped \(\hbox {TiO}_2\), (c) imaginary (Im \(\varepsilon\)) and (d) real (Re \(\varepsilon\)) part for (un)doped \(\hbox {SrTiO}_3\).