Ice Surface and Its Ordering

The most common bulk-phase ice in nature is the hexagonal ice phase Ih, which is widespread in nature and is extremely important in atmospheric and geological studies such as cloud formation, ozone catalysis, and rock weathering. The oxygen atoms in ice Ih are regularly arranged on a hexagonal lattice, i.e., four nearest-neighbor oxygen atoms exist around each oxygen atom, and these four nearest-neighbor oxygen atoms form a quasi-regular tetrahedral arrangement that is compressed along the [0001] direction. Compared with the angle of 109.47° for a perfect regular tetrahedron, the angle between the oxygen atoms forming the tetrahedron within the ice Ih decreases to 109.33° along the [0001] direction and increases to 109.61° perpendicular to the [0001] direction.