Investigating Ice Defects Mobility under an External Bias Potential

Ordinary ice (hexagonal ice Ih) plays an important role in atmospheric processes and in the control of Earth's climate, as well as displaying a variety of properties that are significant for the existence of life. Its tetrahedral proton-disordered structure mediated by hydrogen bonds gives rise to several ways in which structural defects can appear. In addition to displacing entire molecules from their lattice sites, which leads to defect species that also occur in atomic crystals, other imperfections lead to a large diversity of structural defects present only in ice that are related to changes in the hydrogen bonds. Notably, structural defects in ice can decisively determine the properties of the crystal, and it plays a key role by mediating the electrical conductivity through the protons.

In this work, we analyzed the role of the interstitial and vacancy defects in ice conductivity, as well as the defects' mobility under external perturbations through the structure and electronic properties of ice Ih at the interface of gold (Au) electrodes. This is accomplished using a combination of density functional theory (DFT) and non-equilibrium Green's function methods (NEGF).