ABSTRACT
A computable molecular descriptor is a numerical function that encodes a topological feature* of molecular structure such as the number of chlorine atoms, chain branching, ring structure, the substitution pattern of heteroatoms, etc. Many different descriptors have been correlated with chemical properties. The molecular connectivity indices developed by Kier and Hall (1976, 1986) are widely used because they are easy to calculate, they encode structural features that control additive and constitutive chemical properties, and there is no restriction on the type of chemical structure to which they apply. This appendix describes procedures for calculating simple and valence molecular connectivity indices. The zero-and firstorder indices are easy to calculate by hand. Because of the difficulty in identifying all of the components, the second-and higher-order indices are much harder to calculate. It is safer to calculate these with a computer application program. Application programs are available from Hall (1996) and Sabljic (1991).
