LONG-TERM CORRELATIONS IN DIFFUSIVE MOTION OF WATER MOLECULES AND RARE GAS ATOMS IN HELIUM AND ARGON AQUEOUS SOLUTIONS

Collective effects in the diffusive motion of aqueous systems consisting of 10,000 particles (pure water, He and Ar aqueous solutions) are studied, by using the molecular dynamics simulation. The two-particle correlation function DP (t), which is the average scalar product of the displacement vectors of two molecules initially separated by distances lying in certain narrow intervals, is calculated. The calculations were carried out for water molecules and for atoms of rare gases. The presence of He and Ar atoms in 3%-solutions is shown to weakly affect the form of the DP (t) function for water molecules. For He and Ar atoms in aqueous solutions, as well as in the cases of water molecules and Ar atoms in pure liquids, the corresponding correlation functions are found to have a plateau. For a system composed of 1,000 Ar atoms and 9,000 water molecules, no homogeneous liquid solution is obtained even at high pressures.