Structural and configurational properties of nanoconfined monolayer ice from first principles

Abstract

Understanding the structural tendencies of nanoconfined water is of great interest for nanoscience and biology, where nano/micro-sized objects may be separated by very few layers of water. Here we investigate the properties of ice confined to a quasi-2D monolayer by a featureless, chemically neutral potential, in order to characterize its intrinsic behaviour. We use density-functional theory simulations with a non-local van der Waals density functional. An ab initio random structure search reveals all the energetically competitive monolayer configurations to belong to only two of the previously-identified families, characterized by a square or honeycomb hydrogen-bonding network, respectively. We discuss the modified ice rules needed for each network, and propose a simple point dipole 2D lattice model that successfully explains the energetics of the square configurations. All identified stable phases for both networks are found to be non-polar (but with a topologically non-trivial texture for the square) and, hence, non-ferroelectric, in contrast to previous predictions from a five-site empirical force-field model. Our results are in good agreement with very recently reported experimental observations.

12 pages, 8 figures

References in corpus (6)

• Square ice in graphene nanocapillaries
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• 2D ice from first principles: structures and phase transitions
• Effect of water-wall interaction potential on the properties of nanoconfined water
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• Double-layer ice from first principles
• Continuous melting through a hexatic phase in confined bilayer water
• Structure and flow of low-dimensional water
• Simulations of water nano-confined between corrugated planes
• Does twist angle affect the properties of water confined inside twisted bilayer graphene?
• Two-dimensional non-linear hydrodynamics and nanofluidics
• Exotic Vortex Lattices in Binary Repulsive Superfluids