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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
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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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