Foundations of Crystallography

 

Acta Cryst. (2004). A60, 283-293  [ doi:10.1107/S0108767304009420 ]

A Fourier optics approach to the dynamical theory of X-ray diffraction - continuously deformed crystals

G. Mana and C. Palmisano

Synopsis: X-ray diffraction in continuously deformed crystals is reconsidered on the basis of the analogy between X-rays in crystals and two-level systems in quantum mechanics. The different forms of Takagi's equations are shown to be different ways to represent the same propagation equation. An exact solution of Takagi's equations in the case of a constant strain gradient is given and approximation methods are also considered.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 294-305  [ doi:10.1107/S0108767304010293 ]

SPEDEN: reconstructing single particles from their diffraction patterns

S. P. Hau-Riege, H. Szoke, H. N. Chapman, A. Szoke, S. Marchesini, A. Noy, H. He, M. Howells, U. Weierstall and J. C. H. Spence

Synopsis: SPEDEN is a computer program that reconstructs the electron density of single particles from their X-ray diffraction patterns using an adaptation of the holographic method in crystallography. It is designed to deal successfully with sparse, irregular, incomplete and noisy data.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 306-310  [ doi:10.1107/S0108767304010001 ]

Solving the Sayre equations for centrosymmetric structures with a genetic algorithm

Y. Zhou and W.-P. Su

Synopsis: A new method employing Sayre's equations and a genetic algorithm to solve the phase problem is developed for centrosymmetric structures. Compared to simulated annealing, a genetic algorithm is more efficient.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 311-314  [ doi:10.1107/S0108767304010700 ]

Polyhedral truncations as eutactic transformations

M. Torres, J. L. Aragón and A. Gómez-Rodríguez

Synopsis: Vector radiations, as particular examples of eutactic transformations, are defined and studied.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 315-317  [ doi:10.1107/S0108767304011754 ]

Determination of standard uncertainties in fits to pair distribution functions

B. H. Toby and S. J. L. Billinge

Synopsis: A methodology for estimation of statistical uncertainties for parameters fit to pair distribution functions is developed.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 318-321  [ doi:10.1107/S0108767304012188 ]

U₄O₉: atoms in general sites giving the hkl extinctions of special sites

N. C. Popa and B. T. M. Willis

Synopsis: In U₄O₉, the hkl reflections obey the extinction rules for atoms occupying special 12-fold [12(b) of space group I3d] sites. An explanation is given for this effect, which can be generalized to any space group.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 322-325  [ doi:10.1107/S010876730401219X ]

Refinement of the structure of -U₄O₉

R. I. Cooper and B. T. M. Willis

Synopsis: The structure of -U₄O₉ has been refined from single-crystal neutron data in the space group I3d taking into account the findings described in the previous paper.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 326-330  [ doi:10.1107/S0108767304012231 ]

Application of a modified Oszlányi and Süto ab initio charge-flipping algorithm to experimental data

J. S. Wu, J. C. H. Spence, M. O'Keeffe and T. L. Groy

Synopsis: The structures of two crystals have been solved using a new iterative phasing method developed from the `charge-flipping' method.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 331-338  [ doi:10.1107/S0108767304012395 ]

Phasing diffuse scattering. Application of the SIR2002 algorithm to the non-crystallographic phase problem

B. Carrozzini, G. L. Cascarano, L. De Caro, C. Giacovazzo, S. Marchesini, H. Chapman, H. He, M. Howells, J. S. Wu, U. Weierstall and J. C. H. Spence

Synopsis: A new algorithm for determining the phases of diffuse elastic X-ray scattering from a non-periodic object is described.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 339-350  [ doi:10.1107/S0108767304014473 ]

X-ray standing waves in a heterostructure: application to a Zn_1-xCo_xO epilayer on ZnO(00.)-O substrate

Y. Zheng, J. C. Boulliard, A. Soyer and J. F. Pétroff

Synopsis: X-ray standing waves (XSW) were analysed within the dynamical theory for a thin epilayer and the substrate under the epilayer with application to a Zn_1-xCo_xO epilayer on ZnO(00.)-O substrate.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 351-354  [ doi:10.1107/S0108767304010396 ]

A graphical representation of image quality for three-dimensional structure analysis of two-dimensional crystals

A. Cheng and M. Yeager

Synopsis: Data distribution plot for three-dimensional structure analysis of two-dimensional crystals.

Online 24 June 2004

 

Acta Cryst. (2004). A60, 355  [ doi:10.1107/S0108767304014412 ]

High energy electron diffraction and microscopy

Online 24 June 2004

 

Acta Cryst. (2004). A60, 355  [ doi:10.1107/S0108767304015065 ]

Crystal growth for beginners

Online 24 June 2004