issue contents

ISSN: 2053-2733

January 1997 issue

Highlighted illustration

Cover illustration: A structural model of the decagonal Al-Pd-Mn quasicrystal, which consists of clusters represented by decagons and ten pentagons surrounding each decagon. This is obtained from a periodic structure in five-dimensional space by taking a three-dimensional section. Courtesy of A. Yamamoto.

international union of crystallography

Acta Cryst. (1997). A53, 1-6
doi: 10.1107/S0108767397099996

research papers

Acta Cryst. (1997). A53, 7-14
doi: 10.1107/S0108767396009609
link to html
The angle dependence of the anomalous scattering factors for elastic photon–atom scattering is expressed in terms of simple formulae and lookup tables.

Acta Cryst. (1997). A53, 15-27
doi: 10.1107/S0108767396007180
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The diffuse scattering for X-rays or neutrons is derived analytically in a closed form for nanoscale structures distributed according to any distribution function. Results for multilayers, phase separation, domain patterns, surface roughness and `hut' clusters are explicitly given.

Acta Cryst. (1997). A53, 28-34
doi: 10.1107/S0108767396009713
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An algoritm using the representation of the electric fields and wavevectors in a single Cartesian coordinate system with one of the axes perpendicular to the crystal surface is proposed to solve the fundamental equations of multiple-wave dynamical diffraction.

Acta Cryst. (1997). A53, 35-45
doi: 10.1107/S0108767396009804
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The exact analytical solution of the Darwin equations is obtained for the first time for a crystal of finite thickness in the general case where the Bragg planes make an arbitrary angle with the surface of the crystal.

Acta Cryst. (1997). A53, 46-54
doi: 10.1107/S0108767397099984
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The analytical results obtained in the preceeding paper are used in a numerical calculation of the reflecting properties of a number of commonly used neutron monochromator crystals for both symmetric and asymmetric reflection geometries.

Acta Cryst. (1997). A53, 55-62
doi: 10.1107/S0108767396011300
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An equation is derived to describe the diffraction broadening along the meridional direction by a helix of limited length that posesses cumulative azimuthal disorder. The applications of the theory to deoxygenated sickle-cell hemoglobin fibers and to F-actin fibers are discussed.

Acta Cryst. (1997). A53, 63-73
doi: 10.1107/S0108767396011312
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The results of an analytical and numerical study of reflection high-energy electron diffraction (RHEED) show the existence of a fundamental difference between resonance scattering of electrons and Bragg diffraction. It is found that the former is associated with peaks of the one-dimensional density of states (DOS), while the latter is related to forbidden gaps in the spectrum of the DOS.

Acta Cryst. (1997). A53, 74-83
doi: 10.1107/S0108767396011993
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A treatment based on Friedel-pair two-phase invariants shows that single-wavelength anomalous-scattering (SAS) three-phase invariants tend to positive values and yields an origin-shifted tangent formula.

Acta Cryst. (1997). A53, 84-94
doi: 10.1107/S010876739601238X
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The side-face structure of tabular silver bromide crystals is experimentally determined and the preferential lateral growth is explained in terms of a substep mechanism induced by twin planes.

letters to the editor

Acta Cryst. (1997). A53, 101
doi: 10.1107/S0108767396005715
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Nowick's book is criticized for its lack of reference to several important publications on group theory.

book reviews

Acta Cryst. (1997). A53, 102
doi: 10.1107/S0108767396008446
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