Hydration phase diagram for BaO terminated BaTiO$_3$*

This study reveals geometries H{$_2$}O adopts upon adsorption on BaO terminated BaTiO$_3$(BTO) at low to high saturation. A hydration phase diagram for the aforementioned termination is presented, for moderate temperatures, and moderate to ultra high vacuum H$_2$O pressures. Calculations suggest a very stable H$_2$O adsorption for wide range of pressures, including high vacuum conditions (p$_{H_2O}$ 10$^{-12}$ bar). This opens venues for mechanistic studies and hopefully will serve as a guide to condition that might suppress H$_2$O adsorption on BTO for applications where it is undesired.