A simple molecular dynamics simulation for calculating Henry's constant and solubility of gases in liquids

We present a simple and efficient molecular dynamics based method for deter mining Henry's constant of gases dissolved in liquids. The method is an ext ension of an algorithm we presented earlier to study osmosis and reverse os mosis in liquid and gaseous solutions/mixtures. It is based on separating a gaseous compartment in the molecular dynamics system from the solvent usin g a semi-permeable membrane, permeable only to the gas molecules. The syste m is then allowed to come to equilibrium at the desired density and tempera ture and, at equilibrium, Henry's constant can be easily determined using s imple thermodynamics. Since particle insertions or deletions are net needed in this method, it is free of any Limitations in the high-density regime. We have confirmed the accuracy of the proposed method by comparing it with the existing Monte Carlo results for moderate density and showed that it ca n be easily used at high densities as well where insertion/deletion schemes may become quite inefficient. (C) 2000 Elsevier Science B.V. All rights re served.