Kier and Hall valence connectivity indices

Definition:

 - valence connectivity for the k-th atom in the molecular graph

Z_k - the total number of electrons in the k-th atom

- the number of valence electrons in the k-th atom

H_k - the number of hydrogen atoms directly attached to the kth non-hydrogen atom

m = 0 - atomic valence connectivity indices

m = 1 - one bond path valence connectivity indices

m = 2 - two bond fragment valence connectivity indices

m = 3 three contiguous bond fragment valence connectivity indices etc.

References:

1. L. B. Kier, L. H. Hall, Eur. J. Med. Chem., 1977, 12, 307.
2. L. B. Kier, L. H. Hall, J. Pharm. Sci., 1981, 70, 583.
3. L. B. Kier, L. H. Hall, Molecular Connectivity in Structure-Activity Analysis, J. Wiley & Sons, New York, 1986.