Fig. 4

SC lattice and its (1,1,1)-direction. The cube in (a) shows the parallel triangles whose normal direction is (1,1,1) in the simple cubic lattice. If one looks at the cube from the (1,1,1)-direction, then the image is as depicted in (b). Furthermore, if one projects the whole SC lattice to the plane perpendicular to the (1,1,1)-direction, then one gets the image as in (c), where the black, gray and white dots correspond to the three sheets \({\mathcal {A}_{d}}^{(0)}\), \({\mathcal {A}_{d}}^{(1)}\) and \({\mathcal {A}_{d}}^{(2)}\), respectively