Foundations of Crystallography

 

Acta Cryst. (2004). A60, 103  [ doi:10.1107/S0108767304002788 ]

Quantum Crystallography: Electron Density and Bonding, a Microsymposium

S. Manninen

Online 1 March 2004

 

Acta Cryst. (2004). A60, 104-110  [ doi:10.1107/S0108767303029349 ]

Spectral momentum densities in matter determined by electron scattering

E. Weigold, A. S. Kheifets, V. A. Sashin and M. Vos

Synopsis: Electron momentum spectroscopy measurements and cumulant expansion many-body theoretical calculations are used to study the role of electron correlations in the ground electronic states of graphite and polycrystalline aluminium.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 111-119  [ doi:10.1107/S0108767303029350 ]

Electron localization functions obtained from X-ray constrained Hartree-Fock wavefunctions for molecular crystals of ammonia, urea and alloxan

D. Jayatilaka and D. Grimwood

Synopsis: Images of a number of electron localization functions derived from X-ray constrained Hartree-Fock wavefunctions are presented for molecular crystals of ammonia, urea and alloxan.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 120-133  [ doi:10.1107/S0108767303025881 ]

Time-dependent Takagi-Taupin eikonal theory of X-ray diffraction in rapidly changing crystal structures

B. W. Adams

Synopsis: The Takagi-Taupin theory is synthesized with the ray-optical eikonal theory with time dependence explicitly included. Use of the dispersion surfaces in a unified space-time approach is demonstrated for diffraction under the conditions of crystal structure changes on the subpicosecond time scale. The theory is based upon microscopic electromagnetism and thus treats the spatial and temporal coordinates in the same way.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 134-141  [ doi:10.1107/S0108767303027569 ]

Ab initio structure solution by charge flipping

G. Oszlányi and A. Süto

Synopsis: An amazingly simple structure solution algorithm is presented. It works ab initio on high-resolution data in the manner of Fourier recycling, in real space the sign of the charge density below a threshold is simply flipped.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 142-145  [ doi:10.1107/S0108767303029003 ]

A five-dimensional model of dodecagonal Ta-Te quasicrystals with fractal occupation domains

A. Yamamoto

Synopsis: A five-dimensional model of dodecagonal Ta-Te quasicrystals is given. The two crystalline approximant structures can be derived from the model.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 146-152  [ doi:10.1107/S0108767303029659 ]

The crystallographic fast Fourier transform. IV. FFT-asymmetric units in the reciprocal space

A. Kudlicki, M. Rowicka and Z. Otwinowski

Synopsis: Shapes are discussed of FFT-asymmetric units in the reciprocal space, compatible with our crystallographic FFT algorithms. An algorithm is presented for automatic generation of such shapes and points in the reciprocal space are characterized according to their isotropy subgroups. It is shown how both forward and inverse Fourier transforms can be calculated in-place.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 153-157  [ doi:10.1107/S0108767304000224 ]

Statistical approach to the phase problem

H. Xu and H. A. Hauptman

Synopsis: A statistically based formulation of the phase problem as one of constrained global optimization is proposed and tested.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 158-166  [ doi:10.1107/S010876730400162X ]

Hexagonal and trigonal sphere packings. II. Bivariant lattice complexes

H. Sowa and E. Koch

Synopsis: All homogeneous sphere packings, interpenetrating sphere packings and interpenetrating sphere layers were derived which refer to the bivariant lattice complexes of the hexagonal crystal family. Examples of corresponding crystal structures are given.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 167-178  [ doi:10.1107/S0108767303026746 ]

Magnetically ordered quasicrystals: enumeration of spin groups and calculation of magnetic selection rules

R. Lifshitz and S. Even-Dar Mandel

Synopsis: It is shown how to enumerate spin point groups and spin-space-group types for quasicrystals and use them to calculate selection rules for neutron diffraction experiments. Two-dimensional octagonal quasicrystals are considered as an example.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 179-194  [ doi:10.1107/S0108767304002272 ]

Symmetry of magnetically ordered three-dimensional octagonal quasicrystals

S. Even-Dar Mandel and R. Lifshitz

Synopsis: All three-dimensional octagonal spin point groups and spin-space-group types are enumerated and used to calculate selection rules for neutron scattering experiments.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 195-197  [ doi:10.1107/S0108767303029362 ]

`Exact' formulation for -polarization waves of dynamical X-ray diffraction

W. Cho, X. Huang and M. Dudley

Synopsis: Exact and self-consistent formulae for treating -polarization two-beam X-ray diffraction from single crystals are refined within the Laue formalism.

Online 1 March 2004

 

Acta Cryst. (2004). A60, 198-200  [ doi:10.1107/S0108767304003101 ]

Integral lattices

A. Janner

Synopsis: Integral lattices (characterized by an integral metric tensor) are revealed by peaks in the frequency distribution of hexagonal and tetrahedral inorganic compounds and in the molecular form of a RNA quadruplex.

Online 1 March 2004