November 2009 issue
Acta Cryst. (2009). A65, 443-455
A method of structure determination based on an equal-atom point model is described. The method avoids the phase problem, offers high resolution, works with sparse experimental data and provides all possible (quasi-)homometric solutions.
Acta Cryst. (2009). A65, 456-465
An open-ended classification scheme for crystal structures based on Wyckoff sets and affine normalizer groups is proposed.
Acta Cryst. (2009). A65, 466-489
The classification of diffraction spectra of aperiodic crystals based on multiresolution analysis is described.
Acta Cryst. (2009). A65, 490-500
Experimental charge-density study of paracetamol – multipole refinement in the presence of a disordered methyl group
On the basis of high-resolution single-crystal X-ray diffraction data for paracetamol, different approaches (including those based on pseudoatom databases) to modeling of the static experimental electron density in the presence of a dynamically disordered molecular fragment were tested. The electrostatic properties obtained were compared with the results of theoretical single-point periodic calculations.
Acta Cryst. (2009). A65, 501-511
The mineral kettnerite, CaBi(OFCO3), has an order–disorder (OD) structure with a quadratic net built up by more than one kind of layer. Two maximum-degree-of-order (MDO) (1O, 2O) and one non-MDO (2Q) polytypes are derived by stacking of regularly alternating polar OD packets instead of layers. The stacking rule allows the existence of out-of-step, twin and upside-down domains.
Acta Cryst. (2009). A65, 512-527
The method of joint probability distribution functions has been applied to molecular replacement techniques.
Acta Cryst. (2009). A65, 528-531
The success rate of the direct-methods sign-unconstrained S-FFT algorithm has been improved for density functions with only light scatterers. In addition, a closely related but simpler phase-refinement function is introduced, which can also treat positive and negative density peaks.
Acta Cryst. (2009). A65, 532-542
Multiplicative congruential generators, their lattice structure, its relation to lattice–sublattice transformations and applications in crystallography
An analysis of certain types of multiplicative congruential generators – otherwise known for their application to the sequential generation of pseudo-random numbers – reveals their relation to lattice–sublattice transformations and the coordinate description of crystal structures.
Acta Cryst. (2009). A65, 543-545
international union of crystallography
Acta Cryst. (2009). A65, 546
Acta Cryst. (2009). A65, 547-548