Diffraction with a coherent X-ray beam: dynamics and imaging

Techniques for coherent X-ray scattering measurements are detailed. Applications in the study of the dynamics of fluctuations and in lensless high-resolution imaging are described.

On the application of an experimental multipolar pseudo-atom library for accurate refinement of small-molecule and protein crystal structures

A library describing the precise charge density of all chemical groups present in proteins has been developed from the charge-density analysis of several peptide crystals.

The concept of resolution in the domain of rotations

A more economic distortion-free FFT sampling of two-dimensional sections of functions defined on the rotation domain is presented.

A direct phasing method based on the origin-free modulus sum function and the FFT algorithm. XII

A new phase refinement procedure maximizing the origin-free modulus sum function with the FFT algorithm is described so that no explicit use is made of the triple phase relationships. It is general for all space groups and especially effective for low-symmetry ones.

Are intramolecular dynamic electron correlation effects detectable in X-ray diffraction experiments on molecular crystals?

Theoretical structure factors for a range of small molecules are calculated with and without dynamic electron correlation, to establish the size of these effects, and if they can be detected in experimental measurements.

The highest reflection intensity in a resolution shell

The Gumbel–Fisher–Tippett (GFT) extreme-value analysis is applied to evaluate the distribution, expectation value and standard deviation of the intensity J_a of the strongest reflection in a resolution shell.

Ab initio neutron crystallography by the charge flipping method

It is demonstrated that the dual-space charge flipping algorithm is able to solve structures using neutron diffraction data alone. For this purpose, its band flipping variant was introduced which reverses the sign of scattering density only in a zero-centred band. While band flipping is absolutely necessary for developing negative densities, it is the `basic + band' combination of algorithm variants that works most efficiently.

An integer minimal principle and triplet sieve method for phasing centrosymmetric structures

A reliable integer minimal principle model for phasing in all centrosymmetric space groups is presented. It dramatically reduces the number of cycles required to phase a selection of structures in the SnB framework.

Coherent coexistence of nanodiamonds and carbon onions in icosahedral core-shell particles

In icosahedral carbon nanoparticles, the diamond-like core can undergo a reversible topological transition into and coexist coherently with the onion shells.

Hybrid quasiperiodic-periodic structures constructed by projection in two stages

Hybrid quasiperiodic-periodic structures (octagonal, dodecagonal and pentagonal/decagonal) are constructed by cut and projection in two stages.

Tangled (up in) cubes

Tangled cubes contain cycles of edges that form links and knots, yet retain the topology of the edge-net of the cube. The simplest tangled cubes are derived, constrained to have cycles of maximal length eight. Five left-handed and right-handed pairs result. All these examples wrap on the genus-one torus, forming a {6,3} tiling with four hexagonal faces in the torus.

Comment on On the calculation of the electrostatic potential, electric field and electric field gradient from the aspherical pseudoatom model by Volkov, King, Coppens & Farrugia (2006)

Comment on Volkov, King, Coppens & Farrugia [Acta Cryst. (2006), A62, 400–408].

Response to Spackman's comment on On the calculation of the electrostatic potential, electric field and electric field gradient from the aspherical pseudoatom model

Response to Spackman's comment on Volkov, King, Coppens & Farrugia [Acta Cryst. (2006), A62, 400–408].

Report of the Executive Committee for 2005