Charge-cloud interpretation

Interpretating Alkali Iodide Data. The alkali iodide data given above show that the idealized model of ionic crystals is inadequate since 8 9 constant and hp 9 0. To interpret the data one must consider the effects on the iodine 5p population by covalency, deformation of the charge cloud by electrostatic interaction, and deformation by overlap. 

This principle at once provides immediate physical insight into the nature of bonding and its classification, and emphasises the similarity rather than the diversity of different bond types. Briefly, all bonds can be interpreted electrostatically in terms of a charge cloud, provided this is determined wave-mechanically rather than classically. Usually, the form of the charge cloud is inferred from experimental, intuitive and theoretical considerations. 

In this sense any kind of orbital may be used. Only if one wants the orbital picture to include as much as possible of the correct quantum-mechanical description of a given molecule, one must refer to SCF orbitals. This is the basis for taking the Hartree-Fock model as a physical reference point, and for introducing correlation effects as those effects which cannot possibly be interpreted in terms of the charge cloud visualization. 

There are a variety of notations for the repulsion integrals either singly or in standard combinations , each has its own logic and there is no overwhelming reason to choose one or the other. It is sometimes more intuitively acceptable to use the physical interpretation of these integrals as the net repulsion between a charge distribution Xi(Ti)Xfe( i) and Xj 2)xi 2) as a justification for the charge-cloud notation ... 

The above results evidently confirm the validity of a classical interpretation of the effect of a uniform electric field the polarization energy in (11.5.18) is actually associated with an induced electric moment, arising from a field-proportional distortion of the charge cloud, with components determined as in (11.5.21). 

All symbols have their usual meaning in the c.g.s. system of units, as given in Ref. 3. The common interpretation that the central ion sees its ionic cloud at a distance k 1 away is valid for the point-charge model only. For the DH second approximation the ionic cloud can be reduced to a charge located on a spherical surface at k 1 so as to maintain a constant potential at the surface of the central ion. Therefore, it cannot be replaced by a point charge. 

The similarity between the a, a+, o, a, and a0 values also indicates the pyridine nucleus to be of low polarizability. The somewhat greater value of Oy than aY could be ascribed to the extra stabilizing effect on negative charge in the former case (cf. p-N02, a 0.78, a 1.27), but this interpretation is clouded by the fact that oY shows the same trend for the SN1 solvolysis of the pyridine analog of f-cumylchloride.43 Charton has provided evidence for an abnormal electrical effect in a-substituted pyridines as well as quinolines and isoquinolines,47 which he has... 

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