Structure determination from powder diffraction data

David WIF, Shankland K, McCusker LB and Baerlocher Ch, Structure Determination from Powder Diffraction Data, lUCr Monographs on Crystallography 13, Oxford University Press, 2002... 

David, W.I.F., Shankland, K., McCusker, L.B., and Baerlocher, Ch. (2002.) Structure determination from powder diffraction data. Oxford Oxford University Press and lUCr. 

Structure determination from powder diffraction data W. I. F David, K. Shankland, L. B. McCusker,... 

Refs. [i] West AR (1988) Basic solid state chemistry. Wiley New York, pp 323 [ii] Nazri GA, Pistoia G (eds) (2004) Lithium batteries Science and technology Kluwer, Boston, parts I-III [Hi] David WIF, Shank-land K, McCusker LB, Baerlocher C (eds) (2002) Structure determination from powder diffraction data. Oxford University Press, Oxford, pp 337 [iv] Jenkins R, Snyder RL (1996) Introduction to X-ray powder diffractometry. Wiley, New York, pp 403 [v] Baehtz C, Buhrmester T, Bramnik NN, Nikolowski K, Ehrenberg H (2005) Solid State Ionics 176 1647... 

In addition to structure determination from powder diffraction data as described earlier, another area of considerable current interest is the computational prediction of crystal structures based on energy simulation techniques. In such work, the potential energy, E(r), is computed as a function of the set of variables T that define the structure (the unit cell and space group are usually also included as variables in such calculations), and the E r) hypersurface is searched to find the structure of minimum energy. Representative examples of work in this field may be found in Refs. [74-79], and some work involving the use of evolutionary algorithms to carry out the search procedure has been reported [80-82]. 

As discussed in Sect. 3, the first stage of crystal structure determination from powder diffraction data involves determination of the unit cell by indexing the powder diffraction pattern. Clearly it is not possible to proceed with structure solution unless the correct unit cell has been found at this initial stage. Recognizing this issue, a technique employing a GA for indexing powder diffraction data has been reported [88]. The positions of the peaks in a powder diffraction pattern depend on the unit cell dimensions (lattice parameters) [a, b, c, a, ft, y], and the aim of indexing is to determine the correct lattice parameters from... 

W. 1. F. David, K. Shankland, L. M. McCusker, and Ch. Baerlocher eds, Structure Determination from Powder Diffraction Data , International Union of Crystallography Monographs on Crystallography No 13, lUCr/Oxford University Press, Oxford, 2002. 

AB INITIO STRUCTURE DETERMINATION FROM POWDER DIFFRACTION DATA... 

Figure 6.1. The flowchart illustrating crystal structure determination from powder diffraction data. Preliminary processing and indexing are described in Chapters 4 and 5, respectively, and have been assumed accomplished at an earlier stage. Structure completion and Rietveld refinement are described in Chapter 7.

Therefore, novel techniques potentially applicable to solving crystal structures are under continuous testing and development. A recent collective monograph on the structure determination from powder diffraction data provides an excellent discussion of the problem and introduces different approaches that may be used in its solution. In this chapter, unconventional structure solution methods are only briefly reviewed most of them are still controversial and do not always work well with different kinds of compounds and data, although solutions of several complex structures have been demonstrated. Summarized below are the genetic algorithm, maximum entropy, maximum likelihood, and simulated annealing methods. 

A.J. Markvardsen, W.I.F. David, and K. Shankland, A maximum-likelihood method for global-optimization-based structure determination from powder diffraction data, Acta Cryst. ASS, 316 (2002). 

R. Peschar, A. Etz, J. Jansen and H. Schenk, Direct methods in powder diffraction - basic concepts, in Structure determination from powder diffraction data. lUCr monographs on crystallography 13. W. I. F. David,... 

C. Giacovazzo, A. Altomare, M. C. Burla, B. Carrozzini, G. L. Cascarano, A. Guagliardi, A. G. G. Molitemi, G. Polidori and R. Rizzi, Direct methods in powder diffraction - applications, in Structure determination from powder diffraction data. lUCr monographs on crystallography 13. W. I. F. David, K. Shankland, L.B. McCusker, and Ch. Baerlocher, Eds., Oxford University Press, Oxford, New York (2002). 

K.D.M. Harris and M. Tremayne, Crystal structure determination from powder diffraction data, Chem. Mater. 8, 2554 (1996). 

P. Norby, A.N. Christensen, and I.G.K. Andersen, Hydrothermal Preparation of Zeolite Li-A(BW), LiAlSi04 H20, and Structure Determination from Powder Diffraction Data by Direct Methods. Acta Chem. Scand. Sen, A, 1986, 40, 500-506. 

Two important fields of interest in powder diffraction research today are ab initio structure determination from powder diffraction data (SDPD) and line profile analysis (LPA). 

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