The structure of molten NaCl is investigated by combining neutron and x-ray diffraction with molecular dynamics simulations that employed interaction potentials with either rigid or polarizable ions. Special attention is paid to the asymptotic decay of the pair-correlation functions, which is related to the small-k behavior of the partial structure factors, where k denotes the magnitude of the scattering vector. The rigid-ion approach gives access to an effective restricted primitive model in which the anion and cation have equal but opposite charges and are otherwise identical. For this model, the decay of the pair-correlation functions is in qualitative agreement with simple theory. The polarizable ion approach gives a good account of the diffraction results and yields thermodynamic parameters (density, isothermal compressibility, Debye screening length, and heat capacity) in accord with experiment. The longest decay length for the partial pair-distribution functions is a factor of â 2.5 times greater than the nearest-neighbor distance. The results are commensurate with the decay lengths found for the effective restricted primitive model, which are much shorter than those found in experiments on concentrated electrolytes or ionic liquids using surface force apparatus.

Original languageEnglish
Article number094504
Number of pages38
JournalJournal of Chemical Physics
Issue number9
Early online date7 Sept 2022
Publication statusPublished - 7 Sept 2022

Bibliographical note

We thank Bob Evans (Bristol) for his encouragement of this work, Pierre Palleau (Grenoble) for his help with the neutron diffraction experiment, and Phil Jones (Bath) for his glass blowing expertise. The Bath group acknowledges the EPSRC for support via Grant No. EP/G008795/1. T.U. would like to thank the Japan Society for the Promotion of Science (JSPS) for financial support (Grant Nos. 20H02430 and 16H03903) and the Scientist Exchange Program between the JSPS and Royal Society.

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


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