Exact bridge correlation function in water system; Interest for soft condensed matter
Résumé
The SPC/E model of water (one Lennard-Jones core and three partial charges) has been studied by combining Monte Carlo simulation and Molecular Integral Equation numerical techniques. The former provides data on a limited range of distances due to the finite size of the simulation cell while the latter usually assumes the HNC approximated closure which ignores the so-called and a priori unknown bridge function, holy grail in such liquid state theory. It is only the self-consistent addition of both approaches and the use of powerful numerical algorithms that enable to extract exact pair distribution function, structure factor, direct correlation function and, last but not least, bridge function on the whole distance and scattering vector ranges. The strong angular anisotropy of the H2O-H2O correlations is analyzed in terms of projections onto generalized spherical harmonics. The complete and exact knowledge of the bulk water correlations opens the route to efficient numerical theories of solvation properties, so important in soft condensed and biological matters