We also calculated the permittivites of composites with unit cells that were too large to simulate quantum mechanically. We focused on anisotropic inclusions, with rods containing up to 56 silver atoms and aspect ratios of 14:2 and disks containing up to 392 atoms (also with aspect ratio 14:2). Volume loadings were varied by starting with a cell with two layers of MgO around inclusions and then sequentially adding layers of matrix. We approximated the dimensions of the inclusions using multiples of the dimensions of the 2x2x3 rod and 3x3x2 disk studied above (details in Sec. S10) and used an ellipsoidal model with the optimal parameters as fit above. We note that at large aspect ratios, inclusions shapes may be better approximated using cuboids or cylinders, which we explore in Sec. S9. The dependence of relative permittivity on inclusion size and volume loading for these inclusions is presented in Fig. . The volume ratio and anisotropy trends observed in quantum dynamics are conserved for the large inclusions in the FEM: The relative permittivity increases monotonically with the volume ratio. Small increases with axis ratios are seen for rod-like inclusions, when the inclusion is oriented parallel to the field, and small decreases are seen in perpendicular orientations [see Fig. ]. The aspect ratio dependence of the permittivity is stronger for disks, as seen in Fig. (b), where each axis ratio represents a significantly larger number of atoms (and polarizable electrons) in the inclusion. It is worth noting the incipient saturation behaviour for larger rods in parallel orientation to the field, at higher volume loadings. The requirement of a dielectric interface presents an upper limit to the volume loading that can be treated with the present FEM, and the higher loadings presented here for large rods approach that limit.