Acta Crystallographica Section A

Foundations of Crystallography

Volume 54, Part 6 Number 2 (November 1998)

Cover illustration: Power spectrum of a high-resolution electron-microscopy image of NiAl <110>. The image calculation includes a realistic phonon spectrum by coupling the `molecular dynamics' and `multislice' simulation techniques. The diffuse background, satellite peaks and bands mirror the effect of thermal diffuse scattering and correlated atom vibrations. Courtesy of G. Möbus, T. Gemming and P. Gumbsch.

research papers
short communications
book reviews
books received
international union of crystallography

research papers

Acta Cryst. (1998). A54, 957-970 [doi:10.1107/S0108767398003742]

The Probability Distribution of Structure Factors with Non-Integral Indices. I. The P1 Case

C. Giacovazzo and D. Siliqi

Synopsis: The probability distribution of structure factors with non-integral indices is derived in P1.

Acta Cryst. (1998). A54, 971-996 [doi:10.1107/S010876739800539X]

Accurate Charge-Density Studies as an Extension of Bayesian Crystal Structure Determination

P. Roversi, J. J. Irwin and G. Bricogne

Synopsis: Algorithms capable of performing accurate charge-density studies have been implemented within the existing computer program BUSTER, as part of a comprehensive programme for doing crystallography within a Bayesian theory of crystal structure determination. Model studies on noise-free synthetic data sets for [alpha] -glycine, silicon and beryllium show that all-electron calculations give rise to artefacts when a uniform prior prejudice is used, while valence-only calculations using valence monopole priors are essentially free from artefacts.

Acta Cryst. (1998). A54, 997-1005 [doi:10.1107/S0108767398005996]

Noncentrosymmetric Structure of a Decagonal Al₇₀Mn₁₇Pd₁₃ Quasicrystal

S. Weber and A. Yamamoto

Synopsis: The first detailed X-ray structure analysis of a decagonal quasicrystal with a noncentrosymmetric space group is presented.

Acta Cryst. (1998). A54, 1006-1013 [doi:10.1107/S0108767398006539]

Thermal Diffuse Scattering in Angular-Dispersive Neutron Diffraction

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

Synopsis: The theoretical treatment is given of one-phonon thermal diffuse scattering (TDS) in angular-dispersive neutron diffraction. Just as for time-of-flight neutron diffraction, forbidden TDS regions exist for slower-than-sound neutrons.

Acta Cryst. (1998). A54, 1014-1018 [doi:10.1107/S0108767398006965]

Average Unit Cell of the Fibonacci Chain

J. Wolny

Synopsis: An average unit cell for the Fibonacci chain has been constructed in physical space. An analytical expression for the diffraction peak intensities has been derived.

Acta Cryst. (1998). A54, 1019-1027 [doi:10.1107/S0108767398004048]

Ab Initio Calculation of the Structure Factors and Compton Profiles of Cubic Silicon Carbide

D. Ayma, M. Rérat, R. Orlando and A. Lichanot

Synopsis: The charge density, structure factors and Compton profiles of SiC-3C have been calculated at the Hartree-Fock and density functional theory levels. The properties of SiC-3C compare very well with those of semiconductors having the same structure as silicon, diamond and cubic boron nitride.

Acta Cryst. (1998). A54, 1028-1033 [doi:10.1107/S0108767398008150]

Structural Phase Transition Nomenclature. Report of an IUCr Working Group on Phase Transition Nomenclature

J.-C. Tolédano, A. M. Glazer, Th. Hahn, E. Parthé, R. S. Roth, R. S. Berry, R. Metselaar and S. C. Abrahams

Synopsis: A compact and intuitive nomenclature is recommended for naming each phase formed by a given material in a sequence of phase transitions as a function of temperature and/or pressure. The most commonly used label for each phase in a sequence, such as [alpha] , [beta] , , I, II, etc., is included in the new nomenclature.

short communications

Acta Cryst. (1998). A54, 1034-1036 [doi:10.1107/S0108767398007582]

Darwin's approach to X-ray dynamical diffraction in distorted crystals

I. R. Prudnikov

Synopsis: The recursion equations describing X-ray dynamical diffraction in distorted crystals with a three-dimensional deformation field of arbitrary form have been derived. The analytical solution of these equations has been obtained within the kinematical approximation.

book reviews

Acta Cryst. (1998). A54, 1037-1038 [doi:10.1107/S0108767398002645]

The basics of crystallography and diffraction (IUCr Texts on Crystallography, No. 3) by C. Hammond

books received

Acta Cryst. (1998). A54, 1038 [doi:10.1107/S0108767398099966]

Microscopy of semiconducting materials 1997. Institute of Physics Conference Series edited by A. G. Cullis and J. L. Hutchison

Acta Cryst. (1998). A54, 1038 [doi:10.1107/S0108767398099954]

Interfacial wave theory of pattern formation by J.-J. Xu

international union of crystallography

Acta Cryst. (1998). A54, 1039-1040 [doi:10.1107/S0108767398099942]

Prices of IUCr journals

Acta Cryst. (1998). A54, 1041-1044

Subject index to volume A54 (1998)

Acta Cryst. (1998). A54, 1045-1049