Molecular electrostatic field

Nagy, P., J. G. Angyan, and G. Naray-Szabo. 1987. Molecular Electrostatic Fields From Bond Fragments. Int. J. Quant. Chem. 31, 927. 

Kim, E. I., Paliwal, S., Wilcox, C. S., Measurements of molecular electrostatic field effects in edge- to-face aromatic interactions and CH-p interactions with implications for protein folding and molecular recognition. J. Am. Chem. Soc. 

Balogh, T. and Naray-Szabo, G. (1993). Application of the Average Molecular Electrostatic Field in Quantitative Structure-Activity Relationships. Croat. Chem.Acta, 66,129-140. 

Naray-Szabo, G. and Balogh, T. (1993). The Average Molecular Electrostatic Field as a QSAR Descriptor. 4. Hydrophobicity Scales for Amino Acid Residues Alpha. J.Mol.Struct.(Theo-chem), 103, 243-248. 

Structure alignment The superimposition or fitting of the 3-D structures of molecules can be based on electron density, atom positions, molecular electrostatic fields, or secondary structures. This is a crucial step for 3D-QSAR and x-ray structure elucidation. 

Molecular Electrostatic Fields from Bond Fragments. 

Electrostatic interactions are considered to be important attractive forces, due to their relative strength, [59, 116—119]. The molecular electrostatic field which surrounds a binding site guides the correct orientation of the drug [59] and is responsible for the first contact. However, the role of electrostatic interactions as being mainly responsible for high affinity has been questioned due to an often unfavorable solvation-desolvation energy balance. It is difficult to express their contribution in a quantitative manner, due to a number of reasons ... 

Notice that Eq. 6.12 is not the gradient of Eq. 6.5, contrarily to what we showed between the MEP and the molecular electrostatic field. This is due to the absence of a HeUmann-Feynman-like theorem for the electronic subsystem or, in other words, to the explicit dependence of p r,r2) on r. This has been the source of some confusion in the past. Similar comments apply to the other quantities that follow. 

Similar to the distributed-multipole expansion of molecular electrostatic fields, one can derive a distributed-polarizability expansion of the molecular field response. We can start by including the multipole-expansion in the perturbing Hamiltonian term W = Qf(p, where we again use the Einstein sum convention for both superscripts a, referencing an expansion site, and subscripts t, which summarize the multipole components (/, k) in just one index. Using this approximation for the intermolecular electrostatic interaction, the second-order energy correction now reads ... 

MEF = molecular electrostatic field MEP = molecular electro.static potential. 

Organic radicals generally have the unpaired electron in ap orbital, which has orbital angular momentum. However, the weak molecular electrostatic field splits the Ml eomponents and gives Mz, =0 as the lowest state. In this ease g —g . Nevertheless, small deviations from ge do oeeur and can be readily measured, particularly in single erystals, since at a typical 3300-G field, g = 0.0006 for a 1-G shift. 

G. Naray-Szabo and T. Balogh, Viewpoint 7—the average molecular electrostatic field as a QSAR descriptor. Part 4. Hydrophobicity scales for amino acid residues. Journal of Molecular Structure THEOCHEM, 284, 243, 1993. 

---