They involve orienting electrostatic effects and Lennard-Jones sites which may or may not coincide with one or more of the charged sites. The Lennard-Jones interaction accounts for the size of the molecules. It is repulsive at short distances, ensuring that the structure does not completely collapse due to the electrostatic interactions. At intermediate distances it is significantly attractive but non-directional and competes with the directional attractive electrostatic interactions. Some of the more successful simple models are given below.
Models types a, b and c are all planar whereas type d is almost tetrahedral.
Some of the above values are varied slightly by different workers. Such models generally perform better than the simpler models away from the ambient conditions under which they are parameterized. Some of the calculated physical properties of the water models. The agreement of the icosahedral cluster model of water with the O O radial distribution function is in marked contrast to the use of many polarizable and non-polarizable models for water, which do not show any fine structure . Please submit any comments and suggestions you may have.