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Titolo: A new approach for indexing powder diffraction data based on wholeprofilefitting and global optimization using a genetic algorithm
Autore: Kariuki, BM; Belmonte, SA; McMahon, MI; Johnston, RL; Harris, KDM; Nelmes, RJ;
 Indirizzi:
 Univ Birmingham, Sch Chem, Birmingham B15 2TT, W Midlands, England Univ Birmingham Birmingham W Midlands England B15 2TT W Midlands, England Univ Edinburgh, Dept Phys & Astron, Edinburgh EH9 3JZ, Midlothian, Scotland Univ Edinburgh Edinburgh Midlothian Scotland EH9 3JZ Midlothian, Scotland
 Titolo Testata:
 JOURNAL OF SYNCHROTRON RADIATION
,
volume: 6,
anno: 1999,
parte:, 2
pagine: 87  92
 SICI:
 09090495(19990301)6:<87:ANAFIP>2.0.ZU;2S
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 CRYSTALSTRUCTURE DETERMINATION; XRAY; LOWSYMMETRY; PATTERNS; PHASE;
 Keywords:
 powder diffraction; genetic algorithms; indexing; wholeprofile fitting;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Physical, Chemical & Earth Sciences
 Citazioni:
 26
 Recensione:
 Indirizzi per estratti:
 Indirizzo: Kariuki, BM Univ Birmingham, Sch Chem, POB 363, Birmingham B15 2TT, W Midlands, England Univ Birmingham POB 363 Birmingham W Midlands England B15 2TT



 Citazione:
 B.M. Kariuki et al., "A new approach for indexing powder diffraction data based on wholeprofilefitting and global optimization using a genetic algorithm", J SYNCHROTR, 6, 1999, pp. 8792
Abstract
This paper describes a new technique for indexing powder diffraction data. The lattice parameters (unitcell dimensions) {a,b,c,a,beta,gamma} define the parameter space of the problem, and the aim is to find the optimal lattice parameters for a given experimental powder diffraction pattern. Conventional methods for indexing consider the measured positions of a limited number of peak maxima, whereas this new approach considers the whole powder diffraction profile. This new strategy offers several advantages, which are discussed fully. In this approach, the quality of a given set of lattice parameters is determined from the profile Rfactor, Rwp obtained following a Le Bailtype fit of the intensity profile. To find the correct lattice parameters (i.e, the global minimum in Rwp), a genetic algorithm has been usedto explore the Rwp(a,b,c,alpha,beta,gamma) hypersurface. (Other methods for global minimization, such as Monte Carlo and simulated annealing, may also be effective. ) Initially, a number of trial sets of lattice parameters are generated at random, and this 'population' is then allowed to evolve subject to well defined evolutionary procedures for mating, mutation and natural selection (the fitness of each member of the population is determined from its value of Rwp). Examples are presented to demonstrate the success and underline the potential of this new approach for indexing powder diffraction data.
ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 05:50:44