According to this picture cubic ice has two populations of molecules. The oxygens of population 1 occupies each point whose coordinates are all integers and also each point with one integral and two half integral (n+1/2) values.

The oxygens of population 2 are displaced by the vector [1/4, 1/4, 1/4].

The oxygen at [0, 0, 0] thus has 4 population 2 neighbors at [1/4, 1/4, 1/4], [1/4, -1/4, -1/4], [-1/4, 1/4, -1/4] and [-1/4, -1/4, 1/4].

As in hexagonal ice there is one hydrogen between any two neighboring oxygens but it belongs to just one of them.

Unlike hexagonal ice the angle of the molecule is arccos(-1/3), which is good but not really what water wants. Hexagonal ice has fewer symmetries and thus enough latitude to make its angles just what it wants.

The oxygens are located like carbon atoms in diamond. There is a scale factor of 4 in the descriptions.