INTEGRAL-EQUATIONS AND SIMULATION STUDIES OF WATERLIKE MODELS

Central force potentials designed to model water are investigated by m eans of integral equation theories and computer simulations. We consid er an associating neutral model which yields molecules with the geomet ry of the water molecule and that incorporates an effective pair poten tial aimed at describing the hydrogen bond interaction. In addition we study a charged version of the Hamiltonian, which provides a realisti c description of the properties of liquid water. These models are anal yzed in the full association limit, which is obtained by imposing a nu mber of bonds per particle compatible with the water geometry, i.e., 2 and 1 for OH and HH correlations, The structure of the neutral model presents remarkable resemblances with that obtained using realistic mo dels of water. In addition, the atomic Ornstein-Zernike theory along w ith the hypernetted-chain closure provides an accurate description of the structure of this anisotropic molecular system. The consideration of the full association limit introduces important improvements in the theoretical description of the charged central force model. The perfo rmance of this approach in the prediction of thermodynamic, structural , and dielectric properties of liquid water is investigated and the re sults compared with simulation and experimental data. (C) 1998 America n Institute of Physics.