Inverse permutation, definition

We collect symmetry operations into various symmetry groups , and this chapter is about the definition and use of such symmetry operations and symmetry groups. Symmetry groups are used to label molecular states and this labelling makes the states, and their possible interactions, much easier to understand. One important symmetry group that we describe is called the molecular symmetry group and the symmetry operations it contains are permutations of identical nuclei with and without the inversion of the molecule at its centre of mass. One fascinating outcome is that indeed for... 

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