Equivalent fcc and bct Structures


	The yellow spheres represent the basic unit of the fcc structure. Imagine that the whole space is filled with spheres repeating this pattern. The red polygon helps to design another way of building the same crystal. If the spheres around this tetragon are considered, we get the picture on the right hand side. Repeating spheres according to this pattern leads to the same structure; the structures represented in these two different ways are equivalent.