Glide plane, double

Double glide plane (pair of planes in centered cells only) Two coexisting glides of 1/2 (related by a centering translation) parallel to and perpendicular to the projection plane e... 

Double glide plane r A pair of 1/2 lattice vectors in the e... 

We conclude this survey with extended systems, where the assembled structures show the translational symmetry characteristic of the crystalline state. The packing of chiral units into a crystal lattice will inevitably involve some type of diastereo-selectivity, either homochiral or heterochiral, although this is fiequently not discussed in crystal stucture reports. If the associations are all homochiral, then an enantiomerically pure crystal will be obtained, and a solution of the racemate will yield a racemic mixture (see section 3). If, on the other hand, heterochiral association (often related by a centre of inversion or glide plane) is favoured, a racemic compound will crystallize. The double helicate [ 02(51)2] " crystallizes with a homochiral association of complexes along the helieal axis (Figure 38). The homochiral columns are then arranged in pseudohexagonal arrays with the ehirality... 

J. M. Bennett (Union Carbide Corp., Tarrytown, N. Y. 10591) There are differences between the space group of L and P-L. In P-L, the c dimension is doubled by electron diffraction, and systematic absences show the presence of two c glide planes. 

Weibullite alternation of two-planes-thick Q layers and double-octahedral H layers, respectively 5 1/2 Q subcells and 3 1/2 H subcells broad interlayer match 6Q / 3 1/2 H composition/structure non-consen/ative boundaries are composed of trigonal prisms represent glide planes in the layer pile. 

AU of the six vinylogous amides with structure 20 reported in the CSD have the supramolecular chemistry shown in Fig. 5.8. However only one (ZAMVEO) assembles using the necessary simple translational motif The remaining five examples assemble using a glide plane or screw axis. These types of symmetry double the crystallographic repeat distance to an undesirable 14-15 A [34]. 

Sphalerite or zinc blende is the chief ore of ZnS. ZnS as well as many of the III-V and II-VI compound semiconductors such as GaAs form a diamond-like stmeture with one type of atom on the fee lattice sites and the other type of atom on every other tetrahedral site. The space group is F43wx (the d-glide plane symmetry in diamond is lost by the fact that different atoms occupy the interstitial sites). Since there are four atoms on the lattice points of the fee unit cell, the stoichiometry is maintained if half of the eight tetrahedral sites are occupied by the second atom. For these systems, the double stacking described above would have different atoms in doubled layers, i.e., A(Zn) A (S) B(Zn) B (S) C(Zn) C (S), etc. This type of structure is the same as shown in Figure 5.9 if the black spots are... 

Glide Operation that is a product of a mirror and a translation that is a fraction of the lattice vector in the plane of the mirror. There are axial glides, double glides, diagonal glides, and diamond glides. 

Figure 21. The Cu 100 -p(2x2)-p2gg monolayer alloy (a) top view illustrating the two orthogonal mirror planes (m) and glide lines (g) with the structure consisting of a double layer c(2x2) CuPd alloy with the p(2x2) periodicity introduced by clock rotation of the outermost CuPd monolayer (b) side view illustrating the major geometric parameters (c) motion of top layer Pd and Cu atoms within the clock rotation [160].

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