Notation for irreducible representations

The symbols formulated by R, S. Mulliken are used to distinguish the irreducible representations of the various point groups. In this section we will outline the general points of the notation and the reader is referred to Mulliken reportf for the details. 

One-dimensional irreducible representations are labeled either A or B according to whether the character of a 2irjn (proper or improper) rotation about the symmetry axis of highest order n is +1 or —1, respectively. For the point groups Wl9 and which have no symmetry axis, all one-dimensional representations are labeled A. For 

Further information on notation is oontained in O, Himne s Molecular spectra and molecular structure, vol. II. Van Noatnmd Reinhold. 

Two-dimensional irreducible representations are labeled E, which should not be confused with the identity element or the identity matrix. 

Three-dimensional irreducible representations can be labeled either T or F usually T is used in electronic problems and F in vibrational problems. 

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