Publication date: May 19, 2018
We report a large-scale density-functional-theory study of the configuration space of water ice. We geometry optimise 74,963 ice structures, which are selected and constructed from over five million tetrahedral networks listed in the databases of Treacy and Deem, and the International Zeolite Association database. All prior knowledge of ice is set aside and we introduce generalised convex hulls to identify configurations stabilised by appropriate thermodynamic constraints. We thereby rediscover all known phases (I to XVII, i, 0 and the quartz phase) except the metastable ice IV. Crucially, we also find promising candidates for ices XVIII through LI. Using the sketch-map dimensionality-reduction algorithm we construct an a priori, navigable map of configuration space, which reproduces similarity relations between structures and highlights the novel candidates. By relating the known phases to the tractably small, yet structurally diverse set of synthesisable candidate structures, we provide an excellent starting point for identifying formation pathways.
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|50.7 MiB||Structures in xyz format for 15,869 ice structures geometry optimised using PBE-DFT in Castep (plane-wave energy cut-off of 490eV, maximum k-point spacing of 2pi * 0.07 inverse Angstrom, and on-the-fly generated ultrasoft pseudopotentials).|
|1007.4 KiB||Properties of all structures (identifier, number of atoms per unit cell, density, configurational energy, and energy with respect to the energy-density convex hull).|