GRAND CANONICAL MONTE-CARLO SIMULATIONS ON AQUEOUS-SOLUTIONS OF NACL AND NADNA - EXCESS CHEMICAL-POTENTIALS AND SOURCES OF NONIDEALITY IN ELECTROLYTE AND POLYELECTROLYTE SOLUTIONS

Grand canonical Monte Carlo computer simulations on [NaCl]aq and [NaDNA]aq in the presence of added salt are reported. The results for the simple electrolyte indicate that a (12,6,1) potential function for the ions in a solvent treated as a dielectric continuum supplemented with a Gurney correction term for desolvation describes the behavior of activity coefficients as a function of concentration quite well over a concentration range of 5-500 mM. The structure of the ion atmosphere is examined and found to provide new insight into structural effects at the onset of the breakdown in Debye-Huckel theory. The results on the NaDNA system in the presence of added simple electrolyte provide an account of the contravariant behavior of nonideality of mobile ions in polyelectrolyte versus simple electrolyte solutions.