+/*
+ * lattice types:
+ *
+ * there is fcc/diamond/zincblende only!
+ *
+ * basis:
+ *
+ * 0: <0.5 0.5 0> <0 0.5 0.5> <0.5 0 0.5> contains 2 atoms
+ * 1: <0.5 -0.5 0> <0.5 0.5 0> <0 0 1> contains 4 atoms
+ * 2: <1 0 0> <0 1 0> <0 0 1> contains 8 atoms
+ *
+ * atoms:
+ *
+ * - type 0:
+ * 1st fcc: <0 0 0>
+ * 2nd fcc: <0.25 0.25 0.25>
+ * -> diag: <0.25 0.25 0.25>
+ *
+ * - type 1:
+ * 1st fcc: <0 0 0> <0.5 0.5 0.5>
+ * 2nd fcc: <0.5 0 0.25> <1.0 or 0.0 0.5 0.75>
+ -> diag: <0.5 0 0.25>
+ *
+ * - type 2:
+ * 1st fcc: <0 0 0> <0.5 0.5 0> <0.5 0 0.5> <0 0.5 0.5>
+ * 2nd fcc: <0.25 0.25 0.25> <0.75 0.75 0.25> <0.75 0.25 0.75>
+ * <0.25 0.75 0.75>
+ * -> diag: <0.25 0.25 0.25>
+ *
+ */