Partial equalization of orbital electronegativity PEOE

To become familar with the algorithm for charge calculation by partial equalization of orbital electronegativity (PEOE) and by a modified Hiickel Molecular Orbital method... 

At the outset of the Partial Equalization of Orbital Electronegativities (PEOE) method [28] is the electronegativity concept in the form of Eq. (11) presented by Mulliken, who put it on a sound theoretical basis [29]. 

Figure 7-4. The procedure for Partial Equalization of Orbital Electronegativities (PEOE).

The three-dimensional nature of the electrostatic potential makes it difficult to simultaneously visualize its spatial distribution and its magnitude. However, we can deal with the electrostatic potential on the van der Waals surface of a molecule, which is of major importance for the molecular contact between a ligand and a receptor. The electrostatic potential can be calculated by a point charges derived from partial atomic charges, the latter of which can be calculated by iterative partial equalization of orbital electronegativity (PEOE), a well-established empirical method for the rapid calculation of charge distributions [104]. 

Partial Equalization of Orbital Electronegativity (PEOE) is an iterative procedure to calculate charge distribution in a molecule based on electronegativities of bonded atoms and the electrostatic potential created by electron transfer that acts against further electron transfer. 

The PEOE method leads to only partial equalization of orbital electronegativities. Thus, each atom of a molecule retains, on the basis of Eq. (12), a residual electronegativity that measures its potential to attract further electrons. It has been shown that the values of residual electronegativities can be taken as a quantitative measure of the inductive effect [35]. 

M-PEOE = modified partial equalization of orbital electronegativities electronegativity... 

DMA = distributed multipole analysis ESP = electrostatic potential GAPT = generalized atomic polar tensor NAP = natural atomic population NMB = natural minimal basis NRB = natural Rydberg basis OMM = overlap multipole moments PEOE = partial equalization of orbital electronegativities RESP = restrained electrostatic potential. 

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