INDEX attractive energy

Polarizability Attraction. AU. matter is composed of electrical charges which move in response to (become electrically polarized in) an external field. This field can be created by the distribution and motion of charges in nearby matter. The Hamaket constant for interaction energy, A, is a measure of this polarizability. As a first approximation it may be computed from the dielectric permittivity, S, and the refractive index, n, of the material (15), where is the frequency of the principal electronic absorption... 

J. Bjerrum (1926) first developed the theory of ion association. He introduced the concept of a certain critical distance between the cation and the anion at which the electrostatic attractive force is balanced by the mean force corresponding to thermal motion. The energy of the ion is at a minimum at this distance. The method of calculation is analogous to that of Debye and Hiickel in the theory of activity coefficients (see Section 1.3.1). The probability Pt dr has to be found for the ith ion species to be present in a volume element in the shape of a spherical shell with thickness dr at a sufficiently small distance r from the central ion (index k). 

There are two types of solute-solvent interactions which affect absorption and emission spectra. These are universal interaction and specific interaction. The universal interaction is due to the collective influence of the solvent as a dielectric medium and depends on the dielectric constant D and the refractive index n of the solvent. Thus large environmental perturbations may be caused by van der Waals dipolar or ionic fields in solution, liquids and in solids. The van der Waals interactions include (i) London dispersion force, (ii) induced dipole interactions, and (iii) dipole-dipole interactions. These are attractive interactions. The repulsive interactions are primarily derived from exchange forces (non bonded repulsion) as the elctrons of one molecule approach the filled orbitals of the neighbour. 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. In polar solvents dipole-dipole inrteractions are important. 

This is the single-electron operator including the electron kinetic energy and the potential energy for attraction to the nuclei (for convenience, the single electron is indexed as electron one). The two-electron operators in eq. (2.4) are defined as the Coulomb, J... 

Here P denotes the density matrix, h contains kinetic energy and electron-nuclear attraction operators [pqllr] and [rllt] are Coulomb repulsion integrals with 3 and 2 indices, respectively, [pqs] denote one-electron 3-index integrals and is the nuclear-nuclear repulsion term. The form of Equation 4 ensures (11b) that the Coulomb energies are accurate up to second order in the difference between the fitted density and the "exact" density obtained directly from the wavefunctioa... 

We give, in Table I., a list of theoretical values for the attractive constant c [i.e. the factor of — i /i in the above interaction law) for rare gases and some other simple gases where the refractive index can fairly well be represented by a dispersion formula of one term only. The characteristic frequency vj) multiplied by h is in all these cases very nearly equal to the ionisation energy hvj. This may, to a first approximation, justify using the latter quantity in similar cases where a dispersion formula has not yet been determined. It is seen that the values of... 

In terms of intermolecular interactions, the boiling point represents the temperature at which molecules possess enough thermal energy to overcome the various intermolecular attractions binding the molecules into the liquid (e.g. hydrogen bonds, dipole-dipole attraction, instantaneous-dipole induced-dipole attractions). Therefore the boiling point is also an index of the strength of intermolecular attractive forces. 

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