Journal of Chemical Physics, Vol.103, No.12, 5011-5017, 1995
Direct Numerical-Solution of the Ornstein-Zernike Integral-Equation and Spatial-Distribution of Water Around Hydrophobic Molecules
The Ornstein-Zernike integral equation (OZ equation) has been used to evaluate the distribution function of solvents around solutes, : but its numerical solution is difficult for molecules with a complicated shape. This paper proposes a numerical method to directly solve the OZ equation by introducing the 3D lattice. The method employs no approximation the reference interaction site model (RISM) equation employed. The method enables one to obtain the spatial distribution of spherical solvents around solutes with an arbitrary shape. Numerical accuracy is sufficient when the grid-spacing is less than 0.5 Angstrom for solvent water. The spatial water distribution around a propane molecule is demonstrated as an example of a nonspherical hydrophobic molecule using iso-value surfaces. The water model proposed by Pratt and Chandler is used. The distribution agrees with the molecular dynamics simulation. The distribution increases offshore molecular concavities. The spatial distribution of water around 5 alpha-cholest-2-ene (C27H46) is visualized using computer graphics techniques and a similar trend is observed.
Keywords:HYPERNETTED-CHAIN APPROXIMATION;AQUEOUS-ELECTROLYTE SOLUTIONS;THERMODYNAMIC PROPERTIES;RISM EQUATION;HARD-SPHERES;LIQUID WATER;FLUIDS;MODELS;SIMULATION;HYDRATION