issue contents

Journal logoFOUNDATIONS
ADVANCES
ISSN: 2053-2733

November 1999 issue

Highlighted illustration

Cover illustration: One quadrant of each of four fibre diffraction patterns from disordered polynucleotide fibres. The patterns were calculated for fibres with disorder as follows. Upper left: crystalline (no disorder); upper right: noncrystalline (completely disordered); lower left: discrete rotational disorder and correlated lattice disorder; lower right: random screw disorder. See Stroud & Millane [Acta Cryst. (1996), A52, 812-829].

research papers


link to html
A method is derived from indexing the diffraction patterns of approximant structures from the N-dimensional indexing of the parent quasicrystal. Examples are given for the case of the approximant of the icosahedral phases with special emphasis on the origin of the so-called `systematic accidental' extinctions observed in pentagonal phases.

link to html
Probabilistic formulas for estimating structure factors with indices of mixed type (some are integers and some half-integers) are given. The concept of `quasi-invariant' is fixed.

link to html
The program SIR99 is a versatile tool for direct solution and complete refinement of small and large crystal structures.

link to html
X-ray interference patterns from a finite perfect crystal have been studied theoretically using diamond as a model system.

link to html
Debye–Waller factors for 19 compounds with the sodium chloride structure are given over a temperature range from 1 to 1000 K where appropriate.

link to html
An off-axis ring pattern was observed in the 〈1\bar{1}1〉 zone-axis CBED pattern of NiO, and the pattern was interpreted using a two-Bloch-wave approximation.

link to html
The change of structure-factor phases of several weak reflections of GaAs has been measured by three-beam interferences. Using a modulation technique, phase variations of the order of 1° for a field strength of 1 kV mm−1 were determined.

link to html
Non-uniqueness of the multipole refinement of the electron density in ammonium dihydrogen phosphate and consequences on the topology of the electron density.

link to html
Algebraic expressions for projection operators and symmetry-adapted functions (SAFs) of the icosahedral group for spinor (double-valued) representations are found by using the double-induced technique and eigenfunction method.

short communications


book reviews


Acta Cryst. (1999). A55, 1062
doi: 10.1107/S0108767399011939

international union of crystallography


Follow Acta Cryst. A
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds