Electron charge concentration correlation

This picture closely agrees with predictions of the structural correlation method (Sect. 1.3.5.3, Fig. 1.18) and conforms well to the predictions founded on a study of the regions of charge concentration and charge depletion, as defined by the Laplacian of electron density, to identify the sites of nucleophilic attack of formaldehyde and acetaldehyde [112]. It may easily be interpreted by considering the interactions between the frontier orbitals of reactants. The main... 

Figure 4 Solid line shows pair correlation function obtained via LFT for a liquid composed of polyballs of radius 83 nm in water at room temperature. The charge per polyball is 2000 electron charge units, and the number density of polyballs is 1.0 x I0 cm . The concentration of impurity ions is 9.2 x 10 cm This figure is taken from Ref. 50, where further details of the calculation are given. The two dashed lines refer to results obtained u.sing approximate pair potentials which are described in Ref. 50...

Approximate composition of individual hexaaluminate particles was measured by an analytical electron microscope to elucidate the correlation between hexaaluminate phases (Mn-rich and -poor) and Pr contents in the lattice (Figure 6). Although relative concentration of Sr to A1 was a constant at x=0, the composition of the particles in the sample was separated into two groups from their Sr/Al ratios and Mn contents. Pr ions are preferentially doped in the particles with small Mn/ A1 ratios at x=0.2. With an increase in Pr concentration, the number of Pr-poor particles decreased and their Mn/Al ratios approached to those of Pr-rich particles at x=0.4. The substitution of Mn for Al site compensates excess charge of Pr3+ in the hexaaluminate lattice and leads to an increase of Mn in the hexaaluminate particle. It is considered that ease of reduction-oxidation cycle was influenced by the compensation and gave rise to increase in catalytic activity for... 

Under the Born-Oppenheimer approximation, two major methods exist to determine the electronic structure of molecules The valence bond (VB) and the molecular orbital (MO) methods (Atkins, 1986). In the valence bond method, the chemical bond is assumed to be an electron pair at the onset. Thus, bonds are viewed to be distinct atom-atom interactions, and upon dissociation molecules always lead to neutral species. In contrast, in the MO method the individual electrons are assumed to occupy an orbital that spreads the entire nuclear framework, and upon dissociation, neutral and ionic species form with equal probabilities. Consequently, the charge correlation, or the avoidance of one electron by others based on electrostatic repulsion, is overestimated by the VB method and is underestimated by the MO method (Atkins, 1986). The MO method turned out to be easier to apply to complex systems, and with the advent of computers it became a powerful computational tool in chemistry. Consequently, we shall concentrate on the MO method for the remainder of this section. 

---