Although few crystals share the same lattice distance, a number of examples are known.
Twin crystals share some atoms but their overall crystal structures are offset from each other (as shown by the yellow lines in the picture above).
However, RNA and DNA crystals share common features.
The two adjacent crystals share the same (1, 1, 1) plane; thus,, with an intersection group.
Using this kind of intellectual guide, Friedel (1904 ▸, 1926 ▸, 1933 ▸) proposed a classification of twins based on the geometry of the sole crystal lattice (Bravais, 1851 ▸; Mallard, 1885 ▸; Donnay, 1940 ▸): (i) Merohedral twins where the crystals share the same lattice (this can happen only for non-holohedral structures).
(ii) Twins by reticular merohedry where the crystals share only a fraction, a sublattice, of the crystal lattice; this corresponds, in metals and alloys, to the so-called special boundaries between grains like the famous mirror twin along the (111) direction often observed in the f.c.c.
In a side view it is visible that not only do the crystals share a common orientation on the substrate but the tilt angle of 112.7° of the LMAs in the island-like crystals of type S is perfectly fitting to the inclination of the (001) plane of the needles of type B. Most likely the islands nucleate on the sidewalls of already existing needles.
The Se-Met crystals shared the same space group and similar unit cell dimensions as the wild-type (WT) crystals.
The Se-Met crystals shared the same space group and similar unit cell parameters with the native crystals.
Photonic crystal slabs share almost of the properties with true 3D photonic crystals; however, new issues such as slab thickness or mirror symmetries are determinant in their optical behavior [9].
