The Yukagua model of water

Using the Invariant Expansion technique we show that the Multi-Yukawa closure of the Ornstein Zernike equation has an analytical solution for a model that reproduces well the known structure of water as measured by neutron diffraction. The model is an extension of earlier models based on the BBL model [1,2]: the analytical sticky octupolar potential and the soft version of that potential. In the present work the soft short-ranged effective potential is represented by a sum of Yukawa potentials. The models is tested by Monte Carlo computer simulation The atom–atom pair correlation functions for oxygen–oxygen, oxygen–hydrogen and hydrogen–hydrogen obtained for this new potential are in good agreement with the neutron scattering experiments. Because of its analyticity this model is especially suited for the investigation of the percolation transition for the hydrogen bonds, proposed by Stanley and collaborators [3,4,39,40]. The convergence in the simulations is very fast because the weakly directional octupolar potential have little trouble connecting to the tetrahedral first nearest neighbors. The observation made in the computer simulations is that small changes in the strength of the potential seem to lock in or lock out of the tetrahedral structure. This is interpreted as changes in temperature producing the percolation transition.