Flexibility of network structures

Understanding the flexibility of network structures is important for comprehending how such structures react to changing pressure and temperature as well as intercalation reactions. Some network structures are highly flexible, whereas others are rather rigid. Simple modeling approaches can offer some understanding of this behavior. Rigid tetrahedra can fit together extremely well in the ideal cubic networks represented by cristobalite and sodalite. Significant strain exists in ten other cubic networks examined. High flexibility is found in networks represented by the sodalite, analcite, and rho zeolite structures. The network based on ZrO6 octahedra and PO4 tetrahedra in the ZrP2O7 structure is rigid in the cubic system, and it becomes less rigid when the symmetry is reduced to orthorombic, monoclinic, and triclinic. (C) 1996 Academic Press, Inc.