Figure 10
Top: sketches of the different layer groups: left: p2/b 21/m 2/m (No. 40), right: p1m1 (No. 11). Bottom: layers A, B and C (projection along [001]) – layers A and C possess p2/b21/m2/m symmetry, B and (not shown; inverse sequence along a) p1m1 symmetry. |