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Titolo:
A new approach for indexing powder diffraction data based on whole-profilefitting 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:
0909-0495(19990301)6:<87:ANAFIP>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
CRYSTAL-STRUCTURE DETERMINATION; X-RAY; LOW-SYMMETRY; PATTERNS; PHASE;
Keywords:
powder diffraction; genetic algorithms; indexing; whole-profile 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 whole-profilefitting and global optimization using a genetic algorithm", J SYNCHROTR, 6, 1999, pp. 87-92

Abstract

This paper describes a new technique for indexing powder diffraction data. The lattice parameters (unit-cell 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 R-factor, R-wp obtained following a Le Bail-type fit of the intensity profile. To find the correct lattice parameters (i.e, the global minimum in R-wp), a genetic algorithm has been usedto explore the R-wp(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 R-wp). Examples are presented to demonstrate the success and underline the potential of this new approach for indexing powder diffraction data.

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Documento generato il 21/09/20 alle ore 05:50:44