bond order, \(p_{\text{rs}}\)

https://doi.org/10.1351/goldbook.B00707
Theoretical index of the degree of bonding between two atoms relative to that of a single bond, i.e. the bond provided by one localized electron pair. In @M03996@ theory it is the sum of the products of the corresponding atomic orbital coefficients (weights) over all the occupied molecular spin-orbitals.
Source:
Green Book, 2nd ed., p. 17 [Terms] [Book]