The static dielectric constant and molecular geometries in ambient water studied by reverse Monte Carlo simulations

The static dielectric constant ε0 was calculated for structures of liquid water obtained from Reverse Monte Carlo (RMC) simulations driven by partial radial pair correlation functions on one hand and by neutron- and X-ray structure factors on the other. For this purpose, RMC simulations with over 200 million accepted steps were run for systems containing 6000 atoms. Large fluctuations in the individual ε0 values have been found even for such a large system size which makes the application of the dielectric constant as a constraint in RMC modelling infeasible. As a corollary, however, molecular geometries were obtained which helped cast some light on the inconsistencies revealed earlier between various structural descriptions of water.