Orbits crystallographic

A (crystallographic) orbit is the set of all points that are symmetry equivalent to a point. An orbit can be designated by the coordinate triplet of any of its points. If the coordinates of a point are fixed by symmetry, for example 0, q, then the orbit and the Wyckoff position are identical. However, if there is a free variable, for example z in 0, , z, the Wyckoff position comprises an infinity of orbits. Take the points 0, 0.2478... 

Wondiatschek (1976) uses the term orbit instead of point configuration. Orbit (more exactly crystallographic orbit of points in space groups) and crystallographic point configuration are synonyma. 

For this group there are 11 different Wyckoff positions denoted by letters from a to k. The number of crystallographic orbit points in the primitive unit cell (multiplicity) equals np/Uq where np = 16 is the order of the point group and Uq is the order of the site symmetry group Gg. The number of points in a Wyckoff position and their coordinates are given in the International Tables with respect to the conventional unit cell of the lattice (for the space group D j with a simple Bravais lattice, the... 

Callisto orbits Jupiter at a distance of 1.9 million kilometres its surface probably consists of silicate materials and water ice. There are only a few small craters (diameter less than a kilometre), but large so-called multi-ring basins are also present. In contrast to previous models, new determinations of the moon s magnetic field suggest the presence of an ocean under the moon s surface. It is unclear where the necessary energy comes from neither the sun s radiation nor tidal friction could explain this phenomenon. Ruiz (2001) suggests that the ice layers are much more closely packed and resistant to heat release than has previously been assumed. He considers it possible that the ice viscosities present can minimize heat radiation to outer space. This example shows the complex physical properties of water up to now, twelve different crystallographic structures and two non-crystalline amorphous forms are known Under the extreme conditions present in outer space, frozen water may well exist in modifications with as yet completely unknown properties. 

This is a good indication of strong mixing between Si-Si cr orbitals and C = C 7T orbitals with through-bond conjugation as expected. The molecular structure itself was not very much distorted, as evidenced by the X-ray crystallographic analysis shown in Fig. 2. 

F. H. Allen, J. P. M. Lommerse, V. J. Hoy J. A. K. Howard, G. R, Desiraju, The halogen—O(nitro) supramolecular synthon in crystal engineering a combined crystallographic database and ab initio molecular orbital study , Acta CrystaUogr, Section B, 1997, 53,1006-1016. 

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