We present an analysis of the Advanced Light Source (ALS) x-ray scattering
experiment on pure liquid water at ambient temperature and pressure describ
ed in the preceding article. The present study discusses the extraction of
radial distribution functions from the x-ray scattering of molecular fluids
. It is proposed that the atomic scattering factors used to model water be
modified to include the changes in the intramolecular electron distribution
caused by chemical bonding effects. Based on this analysis we present a g(
OO)(r) for water consistent with our recent experimental data gathered at t
he ALS, which differs in some aspects from the g(OO)(r) reported by other x
-ray and neutron scattering experiments. Our g(OO)(r) exhibits a taller and
sharper first peak, and systematic shifts in all peak positions to smaller
r. Based on experimental uncertainties, we discuss what features of g(OO)(
r) should be reproduced by classical simulations of nonpolarizable and pola
rizable water models, as well as ab initio simulations of water, at ambient
conditions. We directly compare many water models and simulations to the p
resent data, and discuss possible improvements in both classical and ab ini
tio simulation approaches in the future. (C) 2000 American Institute of Phy
sics. [S0021-9606(00)50844-7].