10.6084/m9.figshare.9247673.v1 C. Shi C. Shi O. L. G. Alderman O. L. G. Alderman C. J. Benmore C. J. Benmore Network topology of deeply supercooled water Taylor & Francis Group 2019 Water supercooled liquid modelling pair distribution function 2019-08-03 07:46:49 Journal contribution https://tandf.figshare.com/articles/journal_contribution/Network_topology_of_deeply_supercooled_water/9247673 <p>Empirical potential structure refinements have been made to recent high-energy x-ray diffraction data, providing molecular models of deeply supercooled water. The average O-O coordination number is found to drop from 5.13 at 293 K to 4.85 at 244 K, within 3.5 Å. Triplet O-O-O bond angle distributions reveal a broad peak centred at 96.4° at 293 K which shifts to 100.0° at 244 K, indicative of the local geometry becoming increasingly tetrahedral with decreasing temperature. However, although the number of non-bonded interstitial molecules between the first and second shells is depleted upon cooling, the number of interstitial molecules forming triplets that are embedded within the hydrogen bonded tetrahedral network at <i>θ</i><sub>OOO</sub> = 53°, remains constant. This is consistent with previous observations of an invariant O-O coordination number with temperature (4.24 out to 3.3 Å) and corresponds to non-bonded molecules positioned at close to half the ideal tetrahedral angle. Both -O-O-O- and hydrogen-bonded -O-H-O- ring length distributions show increases in 6 and 7-membered rings upon supercooling. This is concomitant with a shift and increase in intensity of peaks at r<sub>4</sub> ∼8.7 Å and r<sub>5</sub> ∼10.8 Å in the oxygen-oxygen pair distribution function, which in the models correspond to correlations between adjacent and next-nearest-neighbour hydrogen-bonded rings.</p>