The delocalization energy of molecules can be calculated
approximately using the Huckel approximation, as was
done originally by Huckel.
It is the spreading of valence
electrons over two or more bonds in a chemical compound.
In certain compounds, the valence electrons cannot
be regarded as restricted to definite bonds between
the atoms but move over several atoms in the molecule.
Delocalization occurs particularly when the compound
contains alternating (conjugated) double or triple
bonds, the delocalized electrons being those in the
pi orbitals. The molecule is then more stable than
it would be if the electrons were localized, an effect
accounting for the properties of benzene and other
The energy difference between
the actual delocalized state and a localized state
is called the delocalization energy. Delocalization
of electrons is a feature of metallic bonding.