Hydrogen bonding electron localization function

Fig. 2.8 The low-barrier hydrogen bond between Lysl6 and an oxygen atom of GTP /1-phosphate group. The electron localization function (ELF) is projected on the plane containing the three atoms involved in the LBHB. The red and yellow areas located between the... 

Krijn MPCM, Feil D (1988) Electron density distributions in hydrogen bonds A local density functional study of a-oxalic acid dihydrate and comparison with experiment. J Chem Phys 89 4199-4208... 

L. F. Pacios, Topological descriptors of the electron density and the electron localization function in hydrogen bond dimers at short intermonomer distances, J. Phys. Chem. A 108, 1177-1188 (2004). 

The complete substitution reaction in water was calculated by Pagliai et al. in 2003 [189]. The authors investigated hydrogen bonds from Wannier functions and the electron localization function (ELF) during the reaction. They found the charge at the transition states to be delocalized and, as a result, weakened and shorter lived hydrogens bonds. Similar results were obtained in other investigations [188, 190]. 

Although only a1 and e are used as additional descriptors so far, some others might be useful in the future. One of the most apparent is the local electronic polarizability of the molecule in the vicinity of a surface segment i, which we may represent by a local refractive index n,. Such local polarizability or local refractive index would allow for a refinement of the electrostatic misfit term, which presently only takes into account an average electronic polarizability of organic molecules. It is also likely that the local electronic polarizability is of importance to the strength of hydrogen bonds, which so far in COSMO-RS are only a function of polarity. Finally, from a physical perspective, the vdW interactions should be a function of the local polarizability as well. 

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