title: Chemically feasible hypothetical crystalline networks.
abstract: Our systematic enumeration of 4-connected crystalline networks (that is, networks in which each atom is connected to exactly four neighbours) used recent advances in tiling theory to evolve over 900 topologies. The results are relevant to the structures of zeolites and other silicates, aluminophosphates (AlPOs), oxides, nitrides, chalcogenides, halides, carbon networks, and even to polyhedral bubbles in foams. Given their importance as molecular sieves, ion exchangers, catalysts and catalyst supports, we have applied the results to microporous aluminosilicates and aluminophosphates (zeolites). Zeolite chemistry has to date produced 152 distinct types of structure. However, it was always clear that although many further structures can be synthesised, only a fraction of the mathematically generated networks would be chemically feasible (many are 'strained' frameworks requiring unrealistic bond lengths and bond angles), and that an effective 'filtering' process is needed to identify the most plausible frameworks. Here, we describe the use of computational chemistry methods to calculate optimized structural parameters, framework energies relative to alpha-quartz, volumes accessible to sorption, and X-ray diffraction patterns for systematically enumerated hypothetical 4-connected crystalline frameworks. Structures were treated as silica polymorphs with the empirical formula SiO(2), and their energies were minimized.
authors.affiliation: Davy-Faraday Research Laboratory, The Royal Institution of Great Britain, 21 Albemarle Street, London W1S 4BS, UK.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Foster
authors.forename: Alexandra
authors.initials: A
authors.lastname: Simperler
authors.forename: Robert G
authors.initials: RG
authors.lastname: Bell
authors.forename: Olaf Delgado
authors.initials: OD
authors.lastname: Friedrichs
authors.forename: Filipe A Almeida
authors.initials: FA
authors.lastname: Paz
authors.forename: Jacek
authors.initials: J
authors.lastname: Klinowski
mesh_terms: D003460:Crystallization; D008958:Models, Molecular; D008962:Models, Theoretical; D012825:Silicon / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013672:Technology / Q000379:methods; D014961:X-Ray Diffraction; D017641:Zeolites / Q000737:chemistry
chemical_list: D017641:Zeolites; D012822:Silicon Dioxide; D012825:Silicon