The Intrinsic Shape of the cubic cP124 Clathrate Structure

It is shown how the Periodic Nodal Surface PNS D*&Y** separates perfectly the two partial structures of the cubic cP124 type. Condensed metal‐centered [M@E20] pentagonal dodecahedra of covalently bonded E atoms form a 3‐connected net. This partial structure is embedded in a zeolite‐type labyrinth containing chains of the remaining metal atoms. The shape of this ensemble represents the principle of the intrinsic curvature of solids. The relations of the structure to the β‐manganese structure are discussed in detail. Furthermore, some details concerning the electron balance in the covalent E 100 net are reported.