Model of the Instantaneous Structure of a Liquid

Abstract

THERE has been much speculation and controversy about the molecular structure of liquids1,2. There are three main problems. First, for the more important classes of liquids, such as water, aqueous solutions, organic liquids and molten metals, it is difficult to determine the intermolecular forces because of the general non-additivity and non-sphericity of the pair potentials. Second, even for the simple non-polar liquids, there are at present no adequate analytical relationships between the intermolecular potentials and the bulk properties. Modern computers make it possible to bypass this obstacle by simulating numerically the motions of large numbers of molecules3–6. Thus, for simple liquids such as the condensed elements of group 0 or their isoelectronic counterparts, the molten alkali halide salts, for which accurate pair potentials are available, information on liquid microstructure can be obtained with a comparatively high degree of detail. Finally, the random and complex nature of liquids requires the practically impossible task of presenting all the iV-body distribution functions for a complete description of equilibrium microstructure. A plausible way to gain insight into local geometry is to construct a three-dimensional model of a configuration generated by computer.