deciduous
发表于 2025-3-23 13:04:37
Steven L. Gardiner,Angie Reed GarnerThe array of atoms must conform to one of the 230 space groups. The equivalent points of a position of a space group must be fully occupied by atoms of the same type. This theoretical model is only achieved conceptually, by an ..
CRANK
发表于 2025-3-23 16:36:38
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Palatial
发表于 2025-3-23 18:06:45
Women’s Status and Fertility PatternsThe outward appearance of a crystal is exceptionally variable, but all the variations which occur can be explained in terms of a single fundamental principle. To grasp this, we must first come to terms with the nature of the crystalline state. The following are a few properties that are characteristic of crystals:
记忆法
发表于 2025-3-24 00:44:24
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dowagers-hump
发表于 2025-3-24 05:14:52
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修剪过的树篱
发表于 2025-3-24 08:18:56
Women’s Status and Fertility PatternsBy the term “morphology”, we refer to the set of faces and edges which enclose a crystal.
Dri727
发表于 2025-3-24 12:47:40
Women’s Status and Fertility PatternsUp to now, the only repetition operation that we have used formally has been the lattice translation: the operation of three non-coplanar lattice translations on a point which gives rise to the space lattice.
progestin
发表于 2025-3-24 16:48:43
Women’s Status and Fertility PatternsIn the various lattices, the vectors . must be chosen and associated with a system of suitable crystallographic axes, .. This is not done arbitrarily. Generally, so far as is possible, the choices are made so that the direction of rotation axes, rotoinversion axes and the normals to mirror planes are parallel to . and to .: ..
nitroglycerin
发表于 2025-3-24 22:25:04
Women’s Status and Fertility PatternsAs has been noted, the space groups of the Bravais lattices are those with the highest possible symmetry for the corresponding crystal systems. When the lattice points are now replaced by actual atoms, ions or molecules, they must themselves possess at least the full symmetry of the lattice point if the space group is to remain unchanged.
guardianship
发表于 2025-3-25 00:55:13
https://doi.org/10.1057/9780230111967The 32 point groups are the symmetry groups of many molecules and of all crystals, so long as only the morphology is considered. Space groups give the symmetry not only of crystal lattices, but also of crystal structures.