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

The static dielectric constant 0 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 0 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.