Acta Crystallographica Section A

Foundations of Crystallography

Volume 61, Part 1 (January 2005)



[Issue Author Index][Volume Author Index]
[Cover 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


 

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

Themed issues of Acta Crystallographica Section A on phase transitions

D. Pandey

Online 22 December 2004


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Acta Cryst. (2005). A61, 3-18  [ doi:10.1107/S0108767304020318 ]

Ferroelastic phase transitions: structure and microstructure

E. K. H. Salje, S. A. Hayward and W. T. Lee

Synopsis: The uses of Landau-type theories to describe structural, microstructural and mesostructural features of materials undergoing phase transitions are reviewed.

Online 22 December 2004


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Acta Cryst. (2005). A61, 19-27  [ doi:10.1107/S010876730402598X ]

Molecular dynamics investigations of modulated phases in organic materials

Y. Pan and G. Chapuis

Synopsis: 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.

Online 22 December 2004


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Acta Cryst. (2005). A61, 28-38  [ doi:10.1107/S0108767304019269 ]

Structural phase transitions from and to the quasicrystalline state

W. Steurer

Synopsis: Typical experimental observations of structural phase transitions from and to the quasicrystalline state as well as their microscopic interpretation are reviewed.

Online 22 December 2004


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Acta Cryst. (2005). A61, 39-50  [ doi:10.1107/S0108767304026625 ]

Short-range order and spin-glass-like freezing in A-Mg-R (A = Zn or Cd; R = rare-earth elements) magnetic quasicrystals

T. J. Sato

Synopsis: 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.

Online 22 December 2004


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Acta Cryst. (2005). A61, 51-61  [ doi:10.1107/S0108767304025437 ]

The Peierls transition in low-dimensional electronic crystals

S. van Smaalen

Synopsis: 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).

Online 22 December 2004


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Acta Cryst. (2005). A61, 62-76  [ doi:10.1107/S0108767304025802 ]

Structures, phase transitions and orientational properties of the C60 monomer and polymers

R. Moret

Synopsis: 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.

Online 22 December 2004


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Acta Cryst. (2005). A61, 77-92  [ doi:10.1107/S0108767304023013 ]

Transmission electron microscopy and structural phase transitions in anion-deficient perovskite-based oxides

J. Hadermann, G. Van Tendeloo and A. M. Abakumov

Synopsis: 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.

Online 22 December 2004


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Acta Cryst. (2005). A61, 93-111  [ doi:10.1107/S0108767304024493 ]

Structures and phase transitions in perovskites - a group-theoretical approach

C. J. Howard and H. T. Stokes

Synopsis: 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.

Online 22 December 2004


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Acta Cryst. (2005). A61, 112-121  [ doi:10.1107/S0108767304025991 ]

X-ray studies of the phases and phase transitions of liquid crystals

P. S. Clegg

Synopsis: 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.

Online 22 December 2004


obituaries


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Acta Cryst. (2005). A61, 122-124  [ doi:10.1107/S0108767304029484 ]

John M. Cowley FAA FRS (1923-2004)

A. Moodie

Online 22 December 2004


research papers


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Acta Cryst. (2005). A61, 125-133  [ doi:10.1107/S0108767304025607 ]

Anomalous scattering method in crystallography on the basis of parametric X-radiation

I. D. Feranchuk and A. Ulyanenkov

Synopsis: 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.

Online 22 December 2004


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Acta Cryst. (2005). A61, 134-138  [ doi:10.1107/S0108767304025528 ]

Three-beam diffraction in an elastically strained crystal plate

H. B. Larsen, G. Thorkildsen and E. Weckert

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

Online 22 December 2004


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Acta Cryst. (2005). A61, 139-146  [ doi:10.1107/S0108767304026881 ]

Determination of depth-dependent diffraction data: a new approach

A. Broadhurst, K. D. Rogers, T. W. Lowe and D. W. Lane

Synopsis: 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.

Online 22 December 2004


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Acta Cryst. (2005). A61, 147-152  [ doi:10.1107/S0108767304027746 ]

Ab initio structure solution by charge flipping. II. Use of weak reflections

G. Oszlányi and A. Süto

Synopsis: 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.

Online 22 December 2004


international union of crystallography


 

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Acta Cryst. (2005). A61, 153-158  [ doi:10.1107/S0108767304031204 ]

Notes for authors 2005

Online 22 December 2004


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