Kier shape indices

Definition:

N_SA - the number of non-hydrogen atom in the molecule

ⁿ P - the number of paths of the length nin the molecular graph

r_i - atomic radius of a given atom

r_Ci - atomic radius of the carbon atom in the sp3 hybridization state

References:

1. L. B. Kier, Quant. Struct.-Act. Relat., 1985, 4, 109.
2. L. B. Kier, in: Computational Chemical Graph Theory, D. H. Rouvray (Ed.), Nova Science Publishers, New York 1990.