Figure 4
Magnified views of fragments of the P, D and G surfaces (see Fig. 3), with three-dimensional Euclidean symmetry operations marked on the surfaces. The arcs AB, BC and CA correspond to the two-dimensional in-surface (non-Euclidean) reflections R2, R1 and R3, respectively, for all three surfaces (see main text). Left: The P surface, with symmetry (including isometries that swap sides of the surface; these are coloured differently here for clarity): A, B and C are located at the 12d (site symmetry ), 24h (mm2) and 8c () sites, respectively; AB and BC lie in orthogonal mirror planes, CA is a twofold axis. Middle: The D surface (): A, B and C are located at the 6d (), 12f (222) and 4c () sites, respectively; AB and BC are twofold axes, CA lies in a mirror plane. Right: The G surface (): A and C are located at the 24d and 16a sites, with point-group symmetries and , respectively; B lies on a twofold axis that is normal to the surface. |