Ammonium fluoride’s analogy to ice: Possibilities and limitations

Ammonium fluoride, NH4F, is often seen as an analog to ice, with several of its solid phases closely resembling known ice phases. While ionic and hydrogen-ordered nature puts topological constraints on the ice-like network structures it can form, not clear what consequences these have for NH4F compound formation evolution. Here, we explore computationally reach eventual limits analogy ammonium fluoride. By combining data mining hypothetical networks crystal structure prediction density functional calculations, high-pressure phase diagram host–guest compounds hydrides. Pure departs from behavior above 80 GPa emergence close-packed structures. The predicted stability hydrides shows that act a host small guest species, albeit in topologically severely constraint configuration space. Finally, binary NH3–HF chemical space, where find candidate unsolved polyfluoride phases; among them H2O2 dihydrate.