Fig. 4: Minimum energy paths, obtained at a DFT level (0 K), for various H2O diffusion pathways on the α-Fe2O3(\(1\bar{1}02\)) surface.
From: Rapid oxygen exchange between hematite and water vapor
Oxygen atoms originating from H2O are drawn in blue, oxygen atoms originating from the lattice are red, iron atoms are yellow. Pathway A features H2O diffusion along the zig-zag rows of the surface, pathway B features diffusion in the perpendicular direction. Both the diffusion mechanisms are close in energy and result in the recreation of the HO-H2O water dimers; pathway B involves O exchange between the water and the lattice. The energetic cost of direct desorption is plotted for comparison (black). In the energy plot, squares correspond to the calculated configurations, connected by cl-NEB calculations shown as circles, with the highest point corresponding to the transition state. Rate-limiting steps are indicated by the green arrows. The transition state in path B is visually identical to B2 and therefore is not shown. Structure files and pathway animations are provided in the Supplementary Materials. Source data are provided as a Source Data file.
