Abstract: The Magnesco - Perico' s method of virtual MOspace is performed.Aseries of molecules (including small inorganic molecules, Alkanes, Alcohols, Amines and conjugated hydrocarbons etc.) are calculated at the level in STO-3Gof ab initio.The results show that the similar regularity of distributions of coefficient and energy levels is presented for the localized occupied and the virtual or-bitals.The Localized virtual orbitals and the corresponding Fock matrix elements are transferable.Futhermore the discussion of chemical bond breaking in the free-radical reaction by use of the difference between energies of localized occupied and vertual orbitals is presented.

Key words: Localization, Localization of virtual orbitals, Bond breaking