IV.D205 — Covalent bond

A covalent bond of order k between atoms A and B is a set of k electron winding modes on T^2 that contribute simultaneously to the shell closure of both atoms: k=1 (single bond, e.g., H_2), k=2 (double bond, e.g., O=O), k=3 (triple bond, e.g., N triple-bond N); bond strength increases with k via mode-overlap integrals.