Hermann-Mauguin notation

Hermann-Mauguin notation is a systematic way to describe the symmetry of crystal structures. It uses symbols and numbers to identify the types of symmetry elements—such as axes of rotation, mirror planes, and inversion centers—that a crystal possesses. The notation combines letters and numbers; for example, "4/m" indicates a fourfold rotational axis with a mirror plane. This standardized system helps scientists categorize and compare crystal symmetries accurately, providing a common language for understanding the geometric properties of materials at the atomic level.