Chapter 1 - SYMMETRY OPERATIONS

Abstract

This chapter discusses the symmetry operations and their notation, and the classification of molecules and crystals into the point groups. Symmetry is possessed by atoms, molecules, and infinite crystals. One can operate on them with a symmetry operation that interchanges the positions of various atoms but results in the molecule or crystal looking exactly the same as before the symmetry operation and when the operation is continuously repeated the molecule or crystal continues to be in an equivalent position. For point symmetry operations one point in the body is kept fixed and these operations are associated with a molecule or crystal. The number of such operations for molecules is finite. A symmetry element is a geometric entity, such as a center of inversion, an axis of rotation, or a plane. Symmetry operations are carried out in regard to these symmetry elements or combinations of them.