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Title: Thermodynamics of ice interfaces and structures within a coarse-grained model of water
Author: Ambler, Michael
ISNI:       0000 0004 6348 6378
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2016
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This research applies the capillary wave method (CWM) to quasi-2D systems in order to calculate the solid-liquid coexistence interfacial free energy (γ) of ice-Ic, ice-Ih and ice-0, with water, at 1 atm, within molecular dynamics simulations employing the coarse-grained monatomic water (mW) model. Investigations are performed to determine how the measured interfacial stiffness (~γ) is affected using various: i) order parameters, to distinguish between the solid and the liquid; ii) analysis discretisation, for interface profiling; iii) system thicknesses. The rationality that ice-I nucleation can be catalysed at strong supercooling within a shell of ice-0 is explored. It is found that at 215.2 K such nucleation could occur, forming an ice-0 shell of 3:3 Å thick around a core of ice-Ih. Free energy perturbation is also applied to the mW model using Monte Carlo simulations, in an attempt to increase the Gibbs free energy gap between ice-Ic and ice-Ih to more closely match values previously reported from experiments and ab initio calculations. However, the Gibbs free energy gap is only increased to 5.6 J mol⁻¹, at 240 K, before the ice-Ic and ice-Ih melting temperatures fall to below 240 K; failing to reach the expected value. This suggests that the mW model, despite its successes, does not capture the true mechanism behind the formation ice-Ic and ice-Ih stacking faults at all degrees of supercooling; the formation of which is rather an artefact of the model itself.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QC Physics