Selected D2O and H2O ices and phase transitions among them with Hirshfeld Atom Refinement

Studying ices is crucial for several scientific reasons, especially in fields like planetary science, astrophysics, and environmental science. Among the 23 structures of solid ices deposited in ICSD, in 7 the positions of H/D atoms are not determined, and in 10 only the isotropic ADPs for H/D atoms were refined. With HAR we can get H/D atom positions and ADPs as we have already proved in the case of ice VI and VII. We can also improve the neutron models of ices(as we have done for ice VII). We aim to apply HAR in order to: (a) establish structures of the following polymorphic forms of the D2O and H2O ices: II, III, V and VIII, Ih (hexagonal) and Ic(cubic), (b) improve geometry an establish anisotropic (maybe even anharmonic) ADP parameters for H/D atoms in these structures, (c) study phase transitions among different ices to explain their complex nature and correlate structural phenomena with thermodynamic data.