A voxel grid is an evenly discretized grid in 3D space. The typical discretization size employed for the intervals usually ranges from 0.5 Å to 1.5 Å for most deep learning applications in the scientific literature . The specific values that each voxel assumes depend on the occupancy model that is employed. A binary occupancy model indicates the presence (1) or absence (0) of an atom in that region of space. This occupancy model typically leads to a sparse grid since most voxels have zero value.