Margherita De Marzio, Gaia Camisasca, Maria Martin Conde, Mauro Rovere and Paola Gallo
Top left panel: Snapshot of a slice of water confined in the silica pore. The blue circle contains the “free water,” the water molecules that are not in contact with the substrate.
Bottom left panel: Density profile of the water molecules along the pore radius. The regions occupied respectively by the free water and the “bound water,” water attached to the substrate, are indicated.
Top right panel: The curves represent how the oxygen atoms of the molecules are arranged in shells around a given oxygen atom in the origin at different temperatures. The peaks represent the positions where the different shells are located. The structure is shown for some of the supercooled temperatures investigated.
Bottom right panel: The main result of our computer simulation is given by the behavior of the excess entropy, a fraction of the total entropy, obtained from the oxygen structure of free water. The deviation of the calculated black points from the theoretical (red) curve indicates that water undergoes a change of behavior before and upon approaching the glass transition.