Chemical bonding true wave function

RESONANCE. 1. In chemistry, resonance (or mesomerism) is a mathematical concept based on quantum mechanical considerations (i.e.. die wave functions of electrons). It is also used to describe or express the true chemical structure of certain compounds that cannot be accurately represented by any one valence-bond structure. It was originally applied to aromatic compounds such as benzene, for winch there are many possible approximate structures, none of which is completely satisfactory. See also Benzene. 

At the same time, the formally independent particle nature of DFT allows the application of standard interpretative tools developed for the HF approach. This is true not only for the standard MuUiken population analysis, but also for more sophisticated schemes, like the Natural Bond Orbital (NBO) analysis [9], the Atomic Polarizable Tensor population [10], or the Atom in Molecule (AIM) approach [11]. These tools allow the use of familiar and well known models to analyze the molecular wave function and to rationalize it in terms of classical chemical concepts. In short, DFT is providing very effective quantum... 

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