The molecular orbitals located on certain fragments of a molecular system and spatially
separated from each other as much as possible. The
LMOs 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
MOs (the Foster–Boys procedure) or by minimizing the sum of the exchange (or
Coulomb) repulsion integrals between the occupied
MOs (the Edmiston–Ruedenberg procedure).
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