Acta Crystallographica Section A

Foundations of Crystallography

Volume 62, Part 2 (March 2006)

International School on Mathematical and Theoretical Crystallography

A printed copy of this issue is available for purchase

Cover illustration: Any crystallographic sublattice can be described as the intersection of a unique set of sublattices each of index a power of a distinct prime. Here a two-dimensional sublattice (shown as green spheres) of index 12 in the basic lattice (mesh) is formed by the intersection of two specific sublattices with prime-power indices 2² (yellow and green) and 3 (blue and green). See Rutherford [Acta Cryst. (2006), A62, 93-97].

feature articles
research papers

feature articles

Acta Cryst. (2006). A62, 47-64 [ doi:10.1107/S0108767306000778 ]

Application of modern tensor calculus to engineered domain structures. 1. Calculation of tensorial covariants

V. Kopský

Synopsis: A systematic approach to calculation of the decomposition of material tensors, including magnetic properties, into tensorial covariants is described.

Online 1 March 2006

Acta Cryst. (2006). A62, 65-76 [ doi:10.1107/S010876730600078X ]

Application of modern tensor calculus to engineered domain structures. 2. Tensor distinction of domain states

V. Kopský

Synopsis: Tensor parameters of domain states in ferroic phase transitions are considered. It is shown how to find both primary and secondary parameters from the decomposition of tensors into covariants.

Online 1 March 2006

research papers

Acta Cryst. (2006). A62, 77-92 [ doi:10.1107/S0108767306000766 ]

Unified system of Hermann-Mauguin symbols for groups of material physics. 1. Groups with decomposable lattices

V. Kopský

Synopsis: Amendments of classical concepts of space and crystallographic groups are proposed and a unified system of Hermann-Mauguin symbols described which includes subperiodic groups and groups with semicontinuous and continuous lattices. Symbols of subperiodic groups are correlated with symbols of space groups with decomposable lattices.

Online 1 March 2006

Acta Cryst. (2006). A62, 93-97 [ doi:10.1107/S0108767305038225 ]

Some algebraic properties of crystallographic sublattices

J. S. Rutherford

Synopsis: Methods are provided to establish the standard form and group structure of a geometric sublattice, and to find the common superlattice of greatest index, and common sublattice of least index, of two such sublattices.

Online 1 March 2006

Acta Cryst. (2006). A62, 98-102 [ doi:10.1107/S0108767305031569 ]

Distinction of magnetic non-ferroelastic domains

D. B. Litvin and V. Janovec

Synopsis: Coordinate systems exist in which tensor properties of two magnetic non-ferroelastic domains differ solely by a change in sign.

Online 1 March 2006

Acta Cryst. (2006). A62, 103-108 [ doi:10.1107/S0108767305036950 ]

Quartz aggregates revisited

H. Grimmer

Synopsis: In quartz aggregates formed by coalescence of preformed crystals in the magma or in hydrothermal solution, monoperiodic twins are common and not restricted to the Zinnwald orientation. For certain values of the axial ratio c/a, diperiodic coincidence in the contact plane will appear, which may be related to the frequency of occurrence of various orientations in low- and high-quartz.

Online 1 March 2006

Acta Cryst. (2006). A62, 109-114 [ doi:10.1107/S0108767305033489 ]

Structures of coincidence symmetry groups

Y. M. Zou

Synopsis: This paper considers the decomposition of a coincidence isometry of a lattice into coincidence reflections and the use of decomposition to study the structure of the coincidence symmetry group.

Online 1 March 2006

Acta Cryst. (2006). A62, 115-128 [ doi:10.1107/S0108767305040286 ]

Bilbao Crystallographic Server. II. Representations of crystallographic point groups and space groups

M. I. Aroyo, A. Kirov, C. Capillas, J. M. Perez-Mato and H. Wondratschek

Synopsis: The article reports on the computer databases and group-theoretical tools related to representations of crystallographic point groups and space groups that are available on the Bilbao Crystallographic Server (http://www.cryst.ehu.es).

Online 1 March 2006

Acta Cryst. (2006). A62, 129-135 [ doi:10.1107/S010876730503713X ]

Informational entropy of Fourier maps

A. Menéndez-Velázquez and S. García-Granda

Synopsis: Information theory has been applied to calculate the amount of information and the informational entropy existing in a Fourier map. These values increase enormously when the number of peaks in the map increases, the greater contribution corresponding to the uncertainty related to the network of chemical bonds.

Online 1 March 2006

Acta Cryst. (2006). A62, 136-145 [ doi:10.1107/S0108767305031041 ]

Comparative crystallographic and hydrogen-bonding analysis of cholestane derivatives

Rajnikant, Dinesh and C. Bhavnaish

Synopsis: Crystallographic comparison of some geometrical and structural features are described for a series of cholestane derivatives and an analysis is given of X-HA intra- and intermolecular interactions with the aid of distance-scatter plots.

Online 1 March 2006