Paralocalization energy

The paralocalization energies can also be estimated14 by the simple PMO method. To a first approximation, the energy (PiS) required to remove two atoms simultaneously from a conjugated system is given by ... 

In the case of aromatic systems, this change in n energy corresponds to the removal of two carbon atoms para to one another in a benzene ring [cf. equation (4.44)]. It has therefore been termed the paralocalization energy. Since the same principles should apply to open chain systems or to Diels-... 

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