Structure and Properties of Ice Phase States

The structure, equation of state, mechanical and vibrational properties of single crystals of ices II, VIII, XI and ice in a previously predicted phase bct-4 are studied within the Hartree-Fock method using the density functional theory (B3LYP hybrid functional) with localized Gaussian atomic orbitals as implemented in the “CRYSTAL14” software package. Calculated lattice parameters, elastic moduli of single crystals, and mechanical parameters of polycrystalline samples are shown to meet the criteria of mechanical stability. Parameters of the Vinet equation of state are obtained. Energy band widths and Mulliken atomic charges are determined using obtained energy and spatial distribution of electrons. The frequencies of long-wave vibrations are calculated and vibrational spectra are constructed.