Browsing by Author "Davies, Brian L."
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- ItemCoset Decompositions of Space Groups: Applications to Domain Structure Analysis(Munksgaard Int Publ Ltd, 1997) Dirl, R.; Zbinbr, P.; Davies, Brian L.; Janovec, VáclavLeft- and double-coset decompositions of space groups are systematically analysed by putting the emphasis on the introduction of special auxiliary groups. An algorithm is tailored to exploit the specific structure of space groups. The new results are, amongst others, an efficient alternative method to determine for space groups minimal sets of double-coset representatives and a general formula that gives the structure and number of left cosets that are contained in double cosets. Left-coset and double-coset decompositions of space groups are exploited in domain structure analysis.
- ItemPC software for crystallographic space groups and its application in symmetry analysis of domain structures(Taylor & Francis Ltd, 1997) Davies, Brian L.; Dirl, R.; Janovec, Václav; Zikmund, ZdeněkAn integrated package of programs has been developed to investigate the structures and representations of crystallographic space groups. The programs, written in PASCAL and C, are made user friendly by additional programs using the Oakland C-scape Interface Management System. A Microsoft Windows version of the software is currently being developed using Borland Delphi. For a given phase transition the software identifies all domain states and finds inter alia (i) symmetry groups of all domain states in algebraic form as a conjugate subgroup stratum, (ii) all operations that transform a given domain state into another domain state, (iii) classes of crystallographically equivalent domain pairs, (iv) symmetry groups of ordered and unordered domain pairs. As an illustrative example software results for the triply commensurate charge-density-wave domain states in the 2H polytype TaSe 2 are presented.