Ricerc@Sapienza

A glass is a microscopically disordered solid-like state which can be achieved by any substance, provided that crystallization is avoided by cooling or compression. Simple and molecular liquids, polymers, bio-materials, metals and molten salts can form glasses, thus making the glass transition a rather ubiquitous phenomenon in condensed matter physics. From the phenomenological point of view, on approaching the glass transition the relaxation time of the system increases by many orders of magnitude and the material starts behaving like a solid, although microscopic translation and orientational order is absent. At present, a full theoretical understanding of the glass transition is still lacking.
A recent and very promising route to produce glassy states is provided by chemical vapor deposition, a technique through which it is possible to generate glasses that are extremely stable both thermodynamically and kinetically. In this project we will use molecular dymamics simulations to apply the chemical vapour deposition protocol to water, which is one of the most studied glass-forming substances. We plan to compare the thermodynamic and kinetic properties of the resulting material with the behaviour of the two different forms of glasses that water produces, i.e. the low-density amorphous and the high-density amorphous ices, whose main properties are connected to the anomalous thermodynamic behaviour of water. We will do so by employing recently developed numerical methods based on high-dimensional order parameters, combined with artificial neural networks classification schemes. The final goal of the project is to assess the stability of the glassy water obtained with different water and water-like models, and to characterize its thermodynamic and kinetic properties.