vibeqc.mayer_bond_orders

vibeqc.mayer_bond_orders(result, basis, molecule)[source]

Mayer bond-order matrix, shape (n_atoms, n_atoms).

For closed-shell systems:

B_AB = S_{mu in A} S_{ν in B} (P.S)_muν . (P.S)_νmu

For UHF / UKS we replace (P.S)(P.S) with the spin-resolved definition 2.[(Pa.S)(Pa.S) + (Pb.S)(Pb.S)] which reduces to the closed-shell formula when Pa = Pb = P/2.

Diagonal entries are the “free valence” of each atom. The off- diagonals are the chemically-meaningful bond orders.

Parameters:
  • basis (vibeqc._vibeqc_core.BasisSet)

  • molecule (vibeqc._vibeqc_core.Molecule)

Return type:

ndarray