Dynamics of molecules in crystals from multi-temperature anisotropic displacement parameters. I. Theory

A mean-field model describing the temperature evolution of anisotropic displacement parameters (ADP's) is presented. With this model, ADP's pertaining to different temperatures may be analysed for mutual consistency, for correlations of atomic displacements as well as for contributions from disorder and systematic error.

Dynamics of molecules in crystals from multi-temperature anisotropic displacement parameters. II. Application to benzene (C₆D₆) and urea [OC(NH)₂]

Anisotropic displacement parameters (ADP's) of C₆D₆ and OC(NH₂)₂ from neutron diffraction experiments in the temperature range 12–123 K are analysed with the mean-field model presented in the preceding paper. Some features of the molecular dynamics are derived from the multi-temperature ADP's and found to agree well with those from independent spectroscopic experiments.

Anharmonicity in anisotropic displacement parameters

A model for the anharmonic temperature evolution of anisotropic displacement parameters is developed and tested with X-ray and neutron diffraction data from hexamethylenetetramine measured between 15 and 298 K.

Strategies for structure solution and refinement of small organic molecules from electron diffraction data and limitations of the simulation approach

It is shown that structure solution and refinement of non-linear optically active molecular crystals is possible based on electron diffraction combined with quantum mechanics, packing-energy calculations and direct methods.

SIR2000, a program for the automatic ab initio crystal structure solution of proteins

A new phasing procedure is described, able to solve the ab initio crystal structures of proteins with up to 2000 non-hydrogen atoms in the asymmetric unit.

Statistical dynamical direct methods. I. The effective kinematical approximation

It is shown that, even though the kinematical theory for electron diffraction is not rigorously accurate for transmission electron diffraction except for unrealistically thin samples, the statistical distribution of phases retains many kinematical characteristics.

Atomic scattering factors for K-shell and L-shell ionization by fast electrons

Atomic scattering factors have been calculated for ionization by fast electrons from the K shell for elements in the range Z = 6 to 50 and from the L shell for Z = 20 to 60.

The contraction types of parallelohedra in E⁵

A general process to derive systematically the contraction types of parallelohedra is described. Then numbers of contraction types of parallelohedra in E⁵ are given for each of the 84 contraction families.

Diffraction by one-dimensional paracrystals and perturbed lattices

The paracrystalline and perturbed lattice models of disordered crystals, and their diffraction patterns, are compared in the one-dimensional case.

Bragg-surface dynamical diffraction

The dynamical theory of X-ray diffraction is applied to Bragg-surface diffraction. A solution for the boundary condition of this unusual three-beam diffraction is presented.

Direct phasing in crystallography

Diffraction des rayonnements