SYMMETRY PROPERTIES OF HUCKEL MATRIX

The existence of excessively degenerate eigenvalues occuring often in the Hückel approach is discussed from the point of the topological matrix. First the full symmetry group of the Hückel problem of three typical examples is discussed and its relation to the commonly used geometrical symmetry group is established. Excessive degeneracy of eigenvalues of Hückel spectra may now be interpreted in terms of the irreducible representation of the full Hückel graph group. The results then are generalized to give more extended though no fully general conditions for excessive degeneracies in Hückel eigenvalues spectra. Furthermore conditions for removal of excessive degeneracy are discussed. © 1969 Springer-Verlag.