Highly discriminating distance-based topological index

A new topological indexJ (based on distance sumssi as graph invariants) is proposed. For unsaturated or aromatic compounds, fractional bond orders are used in calculatingsi. The degeneracy ofJ is lowest among all single topological indices described so far. The asymptotic behaviour ofJ is discussed, e.g. whenn → ∞ in CnH2n = 2,Jar π for linear alkanes, andJ → ∞ for highly branched ones.