Definition of point group in English:

point group

noun

Crystallography

Any of the 32 sets of symmetry operations which can be used to characterize three-dimensional lattices and are the basis of the system of crystal classes.
Example sentencesExamples
- A new method was devised to deduce the orientation of the C 3 trimer axis with respect to the unit cell framework without any other input from the x-ray crystallographic analysis than the 222 point group of the unit cell.
- It crystallizes in the hexagonal system; its point group is thought to be 6 / m 2 / m 2 / m, although there is debate on its structure and symmetry.
- Another molecule with the same point group will experience the same number of vibration modes, though not at the same frequency due to a number of factors including the different weights of its constituent atoms.
- When taking into account the point group of the cocrystals (222 corresponding to the orthorhombic space group), the squares of the direction cosines between all C 3 axes and (a, b, c) should be identical.
- In spite of the loss of symmetry caused by methyl groups and other substituents, and by nonplanar ground-state conformations, all-trans-carotenoids are classified according to the C2h symmetry point group.

单词	point group
释义	Definition of point group in English: point group noun Crystallography Any of the 32 sets of symmetry operations which can be used to characterize three-dimensional lattices and are the basis of the system of crystal classes. Example sentencesExamples A new method was devised to deduce the orientation of the C 3 trimer axis with respect to the unit cell framework without any other input from the x-ray crystallographic analysis than the 222 point group of the unit cell. It crystallizes in the hexagonal system; its point group is thought to be 6 / m 2 / m 2 / m, although there is debate on its structure and symmetry. Another molecule with the same point group will experience the same number of vibration modes, though not at the same frequency due to a number of factors including the different weights of its constituent atoms. When taking into account the point group of the cocrystals (222 corresponding to the orthorhombic space group), the squares of the direction cosines between all C 3 axes and (a, b, c) should be identical. In spite of the loss of symmetry caused by methyl groups and other substituents, and by nonplanar ground-state conformations, all-trans-carotenoids are classified according to the C2h symmetry point group.
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