Partial equalization of orbital electronegativity

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 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]. 

Gasteiger J and M Marsili 1980. Iterative Partial Equalization of Orbital Electronegativity - Rapid Access to Atomic Charges. Tetrahedron 36 3219-3288. 

Gasteiger, J., Marsili, M. Iterative partial equalization of orbital electronegativity - a rapid access to atomic charges. Tetrahedron 1980, 36, 3219-3228. 

Grant, J. A., R. L. Williams, and H. A. Scheraga. 1990. Ab Initio Self-Consistent Field and Potential-Dependent Partial Equalization of Orbital Electronegativity Calculations of Hydration Properties of N-Acetyl-N -Methyl-Alanineamide. Biopolymers 30, 929-949. 

No, K. T., J. A. Grant, M. S. Jhon, andH. A. Scheraga. 1990. Determination of Net Atomic Charges Using a Modified Partial Equalization of Orbital Electronegativity Method. 2. Application to Ionic and Aromatic Molecules as Models for Polypeptides, J. Phys. Chem. 94, 4740-4746. 

MPFOF Modified partial equalization of orbital electronegativity... 

With simple aromatic compounds (Tables XVII and XVIII) the effect of structure on sensory qualities is easily recognizable, too. In order to determine electrophilic and nucleophilic centers in aromatic compounds their charge distributions were calculated. The values for the atomic charges were obtained from a computer program which is based on a model for partial equalization of orbital electronegativity (26, 27). This model was extended to1T-systems (28). 

Determination of Net Ionic Charges Using a Modified Partial Equalization of Orbital Electronegativity Method. 1. Application to Neutral Molecules as Models for Polypeptides. 

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. 

No, K.T., Grant, J.A., Jhon, M.S. and Scheraga, H.A. (1990a) Determination of net atomic charges using a modified partial equalization of orbital electronegativity method. 2. Application to ionic and aromatic molecules as models for polypeptides. /. Phys. Chem., 94, 4740-4746. 

---