A qualitative analysis of the radial distribution functions of water on the basis of the model of a continuous random tetrahedrally coordinated network

Abstract

The behavior of the RDF at high values of r can provide an effective criterion of the extent to which any proposed model of water corresponds to its real structure. If the model of water claims to provide a correct description of such structural characteristics as the topology of the H-bonds, the statistics and form of the rings, etc., it must reproduce the nondamping oscillations of G(r) at r<8–9 A and the sharp decrease in the amplitude of the oscillations at larger distances. The frequently employed technique of achieving this behavior of G(r) by the introduction of the radius of correlation rC≈9 A, beyond which it is postulated that G(r)≡0 [1, 8, 15, 20], is purely formal, does not follow organically from the proposed models, and provides no explanation of the reason for the sharp decrease in the intermolecular correlations. At present it appears that only one paper [24] has satisfactorily reproduced the irregular behavior of G(r) at large values of r (by a successful construction of the potential by the Monte Carlo method). Unfortunately, the authors cited did not study the regular features of the coordinates of the particles which were realized, in particular the topology of the H-bonds. In those cases where attempts have been made to carry out a study of this kind, for example in [5, 25, 26], the agreement between the model and experimental RDF is much less satisfactory. Thus further work is still necessary for the construction of a satisfactory structural model of water within the CRTN framework.