Boris Konstantinovich Vainshtein, 1921–1996

Edward Norman (Ted) Maslen, FAA, 1935–1997

Correction for Thermal Diffuse Scattering in Time-of-Flight NeutronDiffraction

A numerical algorithm is described for calculating the TDS correction to Bragg peaks that are observed in time-of-flight neutron diffraction studies on single crystals.

A Tensor Classification of Twinning in Crystals

Four different types of twinning in crystals are recognized, based on a tensor distinction of their properties and on a new and rigorous definition of prototype symmetry.

Modelling Electrostatic Potential from Experimentally Determined Charge Densities. II. Total Potential

A new method for the determination of atomic moments fitted to theoretical or X–X experimental electrostatic potential is described. It is also shown that a reduced set of moments respecting local symmetry and chemical equivalence reproduces accurately V(r) and then can be used in force-field calculations.

Improved Estimation of Structure-Factor Difference Amplitudesfrom Poorly Accurate Data

A method is presented that improves the estimation of structure-factor difference amplitudes by using Bayesian statistics. The method is shown to give significant improvement for poor data and is straightforward to use.

Multislice Method for Large Beam Tilt with Application to HOLZ Effects in Triclinic and Monoclinic Crystals

Three different multislice formulations for large beam tilt are compared and evaluated. The tested multislice formulations are then applied to calculate higher-order Laue-zone reflections in non-orthogonal crystals.

X-ray Scattering by Dislocations in Crystals. General Theory and Application to Screw Dislocations

This paper presents a rigorous theoretical framework for understanding X-ray scattering from dislocations. This theory is then applied to the specific case of screw dislocations.

The Use of Structure Analysis Methods in Combination with Semi-empirical Quantum-Chemical Calculations for the Estimation of Quadratic Nonlinear Optical Coefficients of Organic Crystals

Electron crystallography was combined with quantum-mechanical calculations in order to estimate quadratic nonlinear optical coefficients of two-dimensional organic molecules.

De Nive Sexangula Stellata

The scaling symmetry observed in the morphology of snow crystals is analysed on the basis of the point group of a multimetrical space group of ice.

High-Order Supersatellite Reflections in Labradorite. A SynchrotronX-ray Diffraction Study

High-resolution X-ray synchrotron radiation study of the supersatellites in the feldspar mineral labradorite. Data analysis shows a transverse displacement modulation with a large amplitude.

Evaluation of Reflection Intensities for the Components of Multiple Laue Diffraction Spots by the Maximum-Entropy Method

A maximum-entropy algorithm for deconvoluting intensities of multiple Laue diffraction spots is described. Test results have shown that this method is capable of producing high-quality data without the requirement of data redundancy.

Dynamical Diffraction in Periodic Multilayers

Extra reflectivity curves, calculated numerically for various periodic multilayers using the optical-matrix method, are used to test the dynamical theory of diffraction.

Anisotropic Thermal Vibrations and Dynamical Electron Diffraction by Crystals

General expressions are derived for the elastic and absorptive atomic scattering amplitudes and for the general case of anisotropic thermal parameters.

Comparing Independently Determined Structures

The application of normal probability methods to a comparison of structural parameters recently derived from independent X-ray and neutron diffraction refinement identifies systematically underestimated uncertainties in addition to significantly differing atomic displacement parameters that previously had been overlooked.

Combined Standard Uncertainties for Interatomic Distance in One-Dimensionally Modulated Crystals

A method is proposed for the calculation of combined standard uncertainties for interatomic distances taking into account covariance terms involved by linear relations of symmetry constraints in one-dimensionally modulated crystals.

On the uniformity of crystallographic orbits

The uniformity characteristics R of crystallographic orbits are studied by the geometrical analysis of the fundamental regions for the corresponding space groups.

Seventeenth General Assembly and International Congress of Crystallography, Seattle, Washington, USA, 8–17 August 1996