Foundations of Crystallography

 

Acta Cryst. (2002). A58, 509-513  [ doi:10.1107/S0108767302011443 ]

Homogeneous sphere packings with triclinic symmetry

W. Fischer and E. Koch

Synopsis: All homogeneous sphere packings with triclinic symmetry have been derived by studying Wyckoff positions P 1a and P 2i.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 514-525  [ doi:10.1107/S0108767302011686 ]

Refinement of crystal structural parameters and charge density using convergent-beam electron diffraction - the rhombohedral phase of LaCrO₃

K. Tsuda, Y. Ogata, K. Takagi, T. Hashimoto and M. Tanaka

Synopsis: Atom positions and anisotropic Debye-Waller factors of the rhombohedral phase of LaCrO₃ have been refined simultaneously with the low-order structure factors for the first time, using the structure analysis method of convergent-beam electron diffraction (CBED).

Online 18 October 2002

 

Acta Cryst. (2002). A58, 526-540  [ doi:10.1107/S0108767302012114 ]

Determination and refinement of disordered crystal structures using evolutionary algorithms in combination with Monte Carlo methods

T. Weber and H.-B. Bürgi

Synopsis: An evolutionary algorithm for the determination and refinement of disordered crystal structures is presented and applied to a real world problem.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 541-546  [ doi:10.1107/S0108767302013636 ]

Reconstruction of the form of a particle from its three-dimensional asymptotic form factor

S. Ciccariello

Synopsis: The leading asymptotic term of the three-dimensional form factor of a homogeneous, finite, smooth, strictly convex and centrosymmetric particle uniquely determines the form of the latter.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 547-551  [ doi:10.1107/S0108767302013922 ]

Direct-method-aided phasing of MIR diffraction data from proteins

Y. X. Gu, W. R. Chang, T. Jiang, C. D. Zheng and H. F. Fan

Synopsis: Direct-method-aided MIR phasing (DMIR) has been proposed based on the direct method of breaking the phase ambiguity intrinsic in protein SIR data.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 552-558  [ doi:10.1107/S0108767302015143 ]

Extinction effect and Borrmann effect of resonant dynamical scattering in the Bragg case

T. Fukamachi, R. Negishi, S. Zhou, M. Yoshizawa and T. Kawamura

Synopsis: The article presents the distinction between the extinction effect and the Borrmann effect on the basis of the X-ray resonant dynamical theory and also discusses the complex dispersion surface.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 559-567  [ doi:10.1107/S0108767302015556 ]

The generalized F constraint in the maximum-entropy method - a study on simulated data

L. Palatinus and S. van Smaalen

Synopsis: A new type of constraint is proposed for use in the maximum-entropy method. It leads to much reduced artifacts in the reconstructed electron-density maps. Tests are performed with simulated data for oxalic acid dihydrate.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 568-573  [ doi:10.1107/S0108767302016318 ]

On the computation of structure factors by FFT techniques

J. Navaza

Synopsis: A rule is given to efficiently calculate molecular scattering factors and crystal structure factors by fast Fourier transform techniques.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 574-579  [ doi:10.1107/S0108767302016744 ]

The crystallographic fast Fourier transform. I. p3 symmetry

M. Rowicka, A. Kudlicki and Z. Otwinowski

Synopsis: An algorithm for computing the discrete Fourier transform of data with threefold symmetry axes is presented. This algorithm is straightforward and easily implemented. It reduces the computational complexity of such a Fourier transform by a factor of 3.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 580-589  [ doi:10.1107/S0108767302015830 ]

Kinematic and dynamical CBED for solving thin organic films at low temperature; experimental tests with anthracene

J. S. Wu and J. C. H. Spence

Synopsis: Low-dose, low-temperature convergent-beam electron diffraction (CBED) patterns from thin organic crystalline films have been used for measurement of structure-factor amplitudes and phases. CBED patterns from thicker regions affected by multiple scattering give structure-factor signs, which are varied for best fit.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 590-597  [ doi:10.1107/S010876730201632X ]

The method of joint probability distribution functions applied to SIR-MIR and to SIRAS-MIRAS cases

C. Giacovazzo and D. Siliqi

Synopsis: SIR-MIR and SIRAS-MIRAS cases are studied via the method of joint probability distribution functions.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 598-604  [ doi:10.1107/S0108767302016331 ]

Crystal structure solution of proteins by direct methods: an automatic procedure for SIR-MIR and SIRAS-MIRAS cases

C. Giacovazzo, M. Ladisa and D. Siliqi

Synopsis: An automatic procedure for solving protein structures via direct methods applied to SIR-MIR and SIRAS-MIRAS cases is described

Online 18 October 2002

 

Acta Cryst. (2002). A58, 605-621  [ doi:10.1107/S010876730201379X ]

Report of a Subcommittee on the Nomenclature of n-Dimensional Crystallography. II. Symbols for arithmetic crystal classes, Bravais classes and space groups

T. Janssen, J. L. Birman, F. Dénoyer, V. A. Koptsik, J. L. Verger-Gaugry, D. Weigel, A. Yamamoto, S. C. Abrahams and V. Kopsky

Synopsis: Specific symbols for R-irreducible groups in 4 and higher dimensions, centrings, Bravais classes, arithmetic crystal classes and space groups (space-group types) are recommended by the Subcommittee on the Nomenclature of n-Dimensional Crystallography in this Second Report. The relationship with higher-dimensional crystallographic groups used in the description of aperiodic crystals is briefly discussed.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 622-623  [ doi:10.1107/S0108767302015088 ]

On the real crystal octahedra

Y. L. Voytekhovsky

Synopsis: A real crystal octahedron is defined as any polyhedron bounded, at least, by some of four pairs of parallel planes being in a standard crystallographic orientation with arbitrary distances between them. All the combinatorially non-equivalent shapes (30 in total) are found and characterized by 2-subordination symbols, automorphism group orders and symmetry point groups. The results are discussed with respect to the diamond crystal morphology.

Online 18 October 2002

 

Acta Cryst. (2002). A58, 624-625  [ doi:10.1107/S0108767302015192 ]

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Online 18 October 2002