Space groups cubic

All atomic positional parameters of the potash alum structure can be assigned to the following general and special equivalent positions of space group Pa3. 

Hexamethylenetetramine, (CH2)6N4, was the first organic molecule to be subjected to crystal structure analysis. The crystals are cubic, with a = 702 pm and measured density p = 1.33 g cm-3. Calculation using the formula Z = pNoV/M = (1.33)(6.023 x 1023)(7.02 x 10 8)3/140 2 shows that there are two molecules in the unit cell. 

Comparison of the crystal structures of (a) y alum NaAl(S04)2-12H20 and (b) p alum CsAl(S04)2 12H20. For clarity the bonds between the M1 atoms and the sulfate groups are represented by broken lines. 

All atomic positions, including hydrogens in the unit cell, can be assigned to the following special positions in space group /43m  

As the structure consists of a body-centered arrangement of (CHoV, molecules, four positional parameters are required for a complete description of the crystal structure. Moreover, the fractional coordinates for carbon and nitrogen can be deduced from relevant chemical data (a) the van der Waals 

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Below a temperature of Toi 260 K, the Ceo molecules completely lose two of their three degrees of rotational freedom, and the residual degree of freedom is a ratcheting rotational motion for each of the four molecules within the unit cell about a different (111) axis [43, 45, 46, 47]. The structure of solid Ceo below Tqi becomes simple cubic (space group Tji or PaS) with a lattice constant ao = 14.17A and four Ceo molecules per unit cell, as the four oriented molecules within the fee structure become inequivalent [see Fig. 2(a)] [43, 45]. Supporting evidence for the phase transition at Tqi 260 K is... 

Sections of the structures of some polysilicides with three-bonded Si atoms. In the stereo image for SrSi2, the positions of the 43 screw axes of the cubic space group P43 3 2 are shown... 

Test measurements were performed on Cuprite, Cu20, for various reasons it has a well-known structure (cubic, space group Pn3m, a = 4.2696, Z = 2) and has been examined by conventional X-ray single crystal diffractometry [5, 6] and by synchrotron radiation in the Tow energy regime [7]. As a consequence of the... 

Calcium hexaboride. An introductory example is represented by the calcium boride (CaB6) in which, however, boron octahedra are not condensed with each other but connected via normal (2e, 2c) bonds. A scheme of the structure is shown in Fig. 4.29. It is cubic, space group, Pm3m, N.221 with ... 

Face-centred cubic, space group Fm3m, N. 225. 

C (diamond), cF8-C, structural type Face-centred cubic, space group Fd3m, N. 227. 

FeSi, cP8, structural type Cubic, space group P2 5, N. 198. 

Body-centred cubic, space group 143m, N. 217. Atomic positions (0, 0, 0 W ) +... 

Cubic, space group Fm3w (No. 225), z Lattice constant KsFeFe a = 8.58 A. 

Topology is cubic, with one independent T site. The structure of analcime has been determined and refined for a long time in the cubic space group [50], even if there is evidence of its non-cubic symmetry. 

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