Energy charge-dipole

This fomuila does not include the charge-dipole interaction between reactants A and B. The correlation between measured rate constants in different solvents and their dielectric parameters in general is of a similar quality as illustrated for neutral reactants. This is not, however, due to the approximate nature of the Bom model itself which, in spite of its simplicity, leads to remarkably accurate values of ion solvation energies, if the ionic radii can be reliably estimated [15],... 

Energy, geometry, dipole moment, and the electrostatic potential all have a clear relation to experimental values. Calculated atomic charges are a different matter. There are various ways to define atomic charges. HyperChem uses Mulliken atomic charges, which are commonly used in Molecular Orbital theory. These quantities have only an approximate relation to experiment their values are sensitive to the basis set and to the method of calculation. 

Hirshfeld and Mirsky (1979) evaluated the relative contributions to the lattice energy for the crystal structures of acetylene, carbon dioxide, and cyanogen, using theoretical charge distributions. Local charge, dipole and quadrupole moments are used in the evaluation of the electrostatic interactions. When the unit cell dimensions are allowed to vary, inclusion of the electrostatic forces causes an appreciable contraction of the cell. In this study, the contributions of the electrostatic and van der Waals interactions to the lattice energy are found to be of comparable magnitude. 

For 3-methyl-anhydro-5-hydroxy-l,2,3,4-oxatriazolium hydroxide (4 R = Me) electron populations, charge densities, and orbital energies, and dipole moment have been calculated by using different semiempirical CNDO/2 methods and ab initio calculations (PEMCSCF) at different levels <891JQ465>. The TT-electrons are found to be highly delocalized and the compound is highly polar. 

If the solute molecule has a dipole moment, it is expected to differ in various electronic energy states because of the differences in charge distribution. If the solvent is nonpolar, then the rough description of the interaction is dipole-induced dipole type. In polar solvents, dipole-dipole interactions also become important. The London forces are always present. For the calculation of dipole-dipole interaction energy, point dipole approximations are made which are poor description for large extended molecules. 

The potential of mean force due to the solvent structure around the reactants and equilibrium electrolyte screening can also be included (Chap. 2). Chapter 9, Sect. 4 details the theory of (dynamic) hydro-dynamic repulsion and its application to dilute electrolyte solutions. Not only can coulomb interactions be considered, but also the multipolar interactions, charge-dipole and charge-induced dipole, but these are reserved until Chap. 6—8, and in Chaps. 6 and 7 the problems of germinate radical or ion pair recombination (of species formed by photolysis or high-energy radiolysis) are considered. 

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