Water Pople model

Apart from Poples model, few water theories accommodate the possibility that hydrogen bonds may not be linear or close to linear. Indeed, practically all major theories of water structure assume that highly bent hydrogen bonds were relatively unimportant. 

A simple model for associated water was needed in which oxygen-oxygen repulsions in water could be equated to those in H20-H30+, which required examination of the energy and associated structural changes on the addition of an unsolvated proton to a liquid water superdipole. Pople s modification103 of Kirkwood s72 static water... 

FIGURE 8-2 Lennard-Jones and Pople electrostatic model for H bonded water (as applied by Schneider, 1812). 

Conductance. Conway, Bockris, and Linton (423) have made a thorough study of proton conductance in water and alcohols. (Sec Section 2.1.5 for a general description.) Their model was basically that of Lennard-Jones and Pople (Fig. 8-2). However, to account for the rate of transfer, some molecules must rotate. This created some doubly filled H bonds, causing further rotation. These steps [Pg.253]

The number of models that describe the structure and properties of liquid water is enormous. They can be subdivided into two groups the uniform continuum models and the cluster or mixture models. The main difference between these two classes of models is their treatment of the H-bond network in liquid water whereas the former assumes that a full network of H-bonds exists in liquid water, in the latter the network is considered broken at melting and that the liquid water is a mixture of various aggregates or clusters. The uniform continuum models stemmed from the classical publications of Bernal and Fowler, Pople, and Bernal.Among the cluster or mixture models, reviewed in refs 2—6 and 12, one should mention the models of Samoilov, Pauling, Frank and Quist, and Nemethy and Scheraga. ... 

Later, Pople concluded that A satisfactory theory must be based on the distortion of the bonds .Pople also noted the inadequacy of the Stockmayer potential for condensed water and said It is necessary to allow for the finite separation of the charges. A simple model containing a distribution of point charges was briefly discussed and discarded as not adequately representing the elastic bend coefficient of a bond. The possibility of a tetrahedrally distributed charge was mentioned, but not pursued. 

G.S. Kell in "Water and Aqueous Solutions" R.A. Home, ed., John Wiley and Sons, New York, N.Y. 1972. The energetic continuum model for liquid water was developed during dissertation research by J.A. Pople, Proc. Roy. Soc. (London),... 

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