Condensed Matter Physics, 2012, vol. 15, No. 2, p. 23606:16
DOI:10.5488/CMP.15.23606
arXiv:1207.3271
Title:
An independent, general method for checking consistency between diffraction data and partial radial distribution functions derived from them: the example of liquid water
Author(s):

Z. Steinczinger
(Budai Nagy Antal Secondary School, H1121, Budapest, Anna utca 1315., Hungary)
,


L. Pusztai
(Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H1525 Budapest, P.O. Box 49., Hungary)

There are various routes for deriving partial radial distribution functions of disordered systems from experimental diffraction (and/or EXAFS) data. Due to limitations and errors of experimental data, as well as to imperfections of the evaluation procedures, it is of primary importance to confirm that the end result (partial radial distribution functions) and the primary information (diffraction data) are consistent with each other. We introduce a simple approach, based on Reverse Monte Carlo modelling, that is capable of assessing this dilemma. As a demonstration, we use the most frequently cited set of "experimental" partial radial distribution functions on liquid water and investigate whether the 3 partials (OO, OH and HH) are consistent with the total structure factor of pure liquid D_{2}O from neutron diffraction and that of H_{2}O from Xray diffraction. We find that while neutron diffraction on heavy water is in full agreement with all the 3 partials, the addition of Xray diffraction data clearly shows problems with the OO partial radial distribution function. We suggest that the approach introduced here may also be used to establish whether partial radial distribution functions obtained from statistical theories of the liquid state are consistent with the measured structure factors.
Key words:
neutron diffraction, partial radial distribution functions, Reverse Monte Carlo modeling
PACS:
61.20.p, 61.25.f, 61.05.fm
