Explanation
The symmetry group for calibrating the internal structure of a crystal is composed of symmetry operations based on the microscopic symmetry elements of a crystal. Starting from the seven major crystal systems, a total of 230 spatial groups can be derived. Each space group contains a translation group as its subgroup. Therefore, all symmetrical elements constituting the space group are infinitely arranged in the entire space lattice image according to the periodic repetition rule. The space group of crystal can be measured by diffraction method. The space group is usually represented by international symbols and consists of two parts: the first part uses capital letters P, A, B, C, I and F to represent the translation group of the space group to describe the periodicity of crystal lattice; The second part is mostly composed of three prescribed bit orders (simply using only one bit order), used to represent the symmetric element system in the dominant direction of a spatial group.
Classification
Fundamental of Material Science -> Structural basis of materials