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We apply the capillary wave method, based on measurements of fluctuations in a ribbon-like interfacial geometry, to determine the solid-liquid interfacial free energy for both polytypes of ice I and the recently proposed ice 0 within a mono-atomic model of water. We discuss various choices for the molecular order parameter, which distinguishes solid from liquid, and demonstrate the influence of this choice on the interfacial stiffness. We quantify the influence of discretisation error when sampling the interfacial profile and the limits on accuracy imposed by the assumption of quasi one-dimensional geometry. The interfacial free energies of the two ice I polytypes are indistinguishable to within achievable statistical error and the small ambiguity which arises from the choice of order parameter. In the case of ice 0, we find that the large surface unit cell for low index interfaces constrains the width of the interfacial ribbon such that the accuracy of results is reduced. Nevertheless, we establish that the interfacial free energy of ice 0 at its melting temperature is similar to that of ice I under the same conditions. The rationality of a core-shell model for the nucleation of ice I within ice 0 is questioned within the context of our results.

SynopsisIJsing general-purpose multicolumn sets, it was found that separations could be increased by increasing analysis time, either by decreasing flow rate or increasing column length. Several examples are shown illustrating the influence of these system variables. The generation of linear calibration curves over extended molecular weight ranges is discussed. In particular, the desirability of using high molecular weight standards to extend the Calibration curve and eliminate extrapolation of the curve is shown. Not using all available gel porosities, i.e., gapped column sets, is shown to be detrimental to the resolution of molecular species. It was found that with the use of sufficiently long column lengths and low flow rates, accurate molecular weights of both narrow and broad molecular weight distribution samples are directly calculable from the chromatogram without the need for peak spreading corrections.

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