Indexing approximants of icosahedral quasicrystals

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.

The joint probability distribution function of structure factors with rational indices. VI. Cases with reduced dimensionality

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.

SIR99, a program for the automatic solution of small and large crystal structures

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

X-ray intensity patterns from finite perfect crystals

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

Lattice dynamics and Debye–Waller factors of some compounds with the sodium chloride structure

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

Anisotropic dispersion of the band structure and formation of ring patterns in CBED

An off-axis ring pattern was observed in the 〈〉 zone-axis CBED pattern of NiO, and the pattern was interpreted using a two-Bloch-wave approximation.

Experimental determination of electric-field-induced differences in structure-factor phases of the order of 2%

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.

Electron density in ammonium di­hydrogen phosphate: non-uniqueness of the multipolar model in simple inorganic structures

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

Algebraic expressions for symmetry-adapted functions of the icosahedral group in spinor space

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.

Dynamical scattering and electron diffraction from thin polymer lamellar crystals – poly(tert-butylethylene sulfide). Erratum

Erratum to Acta Cryst. (1999), A55, 901–907.

Physics of crystal growth

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