issue contents

ISSN: 2053-2733

January 2005 issue

Highlighted illustration

Cover illustration: An experimentally derived plot of the Fermi hole mobility function (FHMF) for urea. The FHMF can be interpreted as a potential energy surface for electron transfer. This plot was obtained from a Hartree-Fock wavefunction constrained to fit measured X-ray diffraction structure factors, using the Tonto program. See Jayatilaka & Grimwood [Acta Cryst. (2004), A60, 111-119].

phase transitions

Acta Cryst. (2005). A61, 1-2
doi: 10.1107/S0108767304033434

Acta Cryst. (2005). A61, 3-18
doi: 10.1107/S0108767304020318
link to html
The uses of Landau-type theories to describe structural, microstructural and mesostructural features of materials undergoing phase transitions are reviewed.

Acta Cryst. (2005). A61, 19-27
doi: 10.1107/S010876730402598X
link to html
Molecular dynamics (MD) has evolved into a reliable technique for simulating incommensurate modulated phases. The application of a compensating external pressure tensor to organic materials allows a better fit to the experimental measurements. An overview of the MD method and its applications is presented here.

Acta Cryst. (2005). A61, 28-38
doi: 10.1107/S0108767304019269
link to html
Typical experimental observations of structural phase transitions from and to the quasicrystalline state as well as their microscopic interpretation are reviewed.

Acta Cryst. (2005). A61, 39-50
doi: 10.1107/S0108767304026625
link to html
Recent experiments on the magnetic properties of A–Mg–R (A = Zn and Mg; R = rare-earth elements) icosahedral quasicrystals are reviewed. Emphasis is placed on the origin of their spin-glass-like behavior; discussion is made based on existing data sets ranging from bulk magnetization to neutron diffraction.

Acta Cryst. (2005). A61, 51-61
doi: 10.1107/S0108767304025437
link to html
An overview is presented of inorganic compounds with low-dimensional electronic structures, and of X-ray diffraction as a tool to study the properties of charge-density waves (CDWs).

Acta Cryst. (2005). A61, 62-76
doi: 10.1107/S0108767304025802
link to html
This review describes how the unique orientational properties of the C60 fullerene molecule influence the structure and phase transitions of the C60 monomer and polymer.

Acta Cryst. (2005). A61, 77-92
doi: 10.1107/S0108767304023013
link to html
Oxidation/reduction reactions in three-dimensional or layered manganites and cuprates are accompanied by the formation of domain structures. The microstructure of several representatives was studied by means of electron diffraction and high-resolution electron microscopy.

link to html
The application to perovskite crystallography of group-theoretical methods, as implemented in the computer program ISOTROPY, is reviewed. The results have been used, in combination with high-resolution X-ray or neutron powder diffraction in fine temperature steps, to study structural phase transitions in perovskites.

link to html
Recent X-ray diffraction studies of liquid crystals are reviewed. The topics are twist grain-boundary phases, antiferroelectric phases studied using resonant diffraction and smectic phases within gel structures.


research papers

link to html
The article presents a comprehensive theoretical description of the anomalous scattering method along with simulated numerical examples. The method is based on physical properties of parametric X-radiation.

link to html
An approximate analytical expression for the three-beam diffraction profile in a crystal plate subjected to elastic strain is derived.

link to html
A direct method for transforming angle-dependent diffraction data into depth-dependent data by the use of regularization techniques is presented, including method validation and application to experimental data.

link to html
A drastic improvement of the original charge-flipping algorithm is presented. The phase space is explored more efficiently by a special treatment of weak reflections in the iteration process. Paradoxically, it is better not to use observed moduli of weak reflections: in the search for a solution, they create only unwanted constraints.

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