Aromatic-fluctuation-index-

An interesting comparison between several aromaticity indices (harmonic oscillator model, nucleus-independent chemical shift, para-delocalization index, aromatic fluctuation index, multicenter indices, atoms-in-molecules theoretical indices and graph-theoretical indices) concluded that the most reliable ones are based on electron delocalization (08JCC1543). 

NBO)-based approaches (iv) aromatic fluctuation index (FLU) by M. Sola and coworkers (v) block-localized wavefunction (BLW) method by P. v. R. Schleyer and Y. Mo and (vi) energy decomposition analysis (EDA) by F. M. Bickelhaupt and coworkers. 

Sola "" aromatic fluctuation index (FLU) (describing the fluctuation of electronic charge between adjacent atoms in a given ring) ... 

Matito E, Duran M, Sola M (2005) The aromatic fluctuation index (FLU) a new aromaticity index based on electron delocalization. J Chem Phys 122 014109... 

Another popular electronic measure of aromaticity is the fluctuation index (FLU) (2005JCP014109). It measures electron fluctuation differences with respect to an aromatic reference system by comparing the contiguous electron delocalization indices (1999JPCA304) along cychc structure. The FLU index is close to 0 in aromatic species and departs from this value in nonaromatic ones. The drawback in this case is similar to that for geometry-based indices, namely the dependence on the reference systems. 

Matito, E., Salvador, P, Duran, M., Sola, M. (2006). Aromaticity measures from fuzzy-atom bond orders (FBO). The aromatic fluctuation (FLU) and the para-delocahzation (PDI) indexes. J. Phys. Chem. A 110,5108-5113. 

This is a fundamental result of actual exact HUR treatment for chemical bonding. However, further application of the ELFp index (4.568) for explaining—for instance— the molecular aromaticity, see Volume III of this set, in terms of geometry of bonding and the amount of quantum fluctuation present, are in progress and will be in the future communicated. 

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