The molecular orbitals located on certain fragments of a molecular system and spatially separated from each other as much as possible. The LMO
s are derived from the electron occupied canonical molecular orbitals by subjecting them to a unitary transformation determined by an appropriate physical criterion, e.g.
by maximizing the sum of squares of the centroids of occupied MO
s (the Foster–Boys procedure) or by minimizing the sum of the exchange (or Coulomb) repulsion integrals between the occupied MO
s (the Edmiston–Ruedenberg procedure).
PAC, 1999, 71, 1919. 'Glossary of terms used in theoretical organic chemistry' on page 1950 (https://doi.org/10.1351/pac199971101919)