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.

    • ‘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.’
    • ‘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.’
    • ‘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.’
    • ‘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.’