Multipole electron densities and atomic displacement parameters in urea from accurate powder X-ray diffraction

The electron density of crystalline urea has been determined based on powder X-ray diffraction data.

Theoretical study of the properties of X-ray diffraction moiré fringes. II. Illustration of angularly integrated moiré images

Using a recently developed moiré-fringe theory of X-ray diffraction, the angularly integrated moiré images of a lightly strained silicon bicrystal having an interspacing gap were simulation-computed over a wide range of crystal thicknesses and incident-beam angular width.

Temperature-dependent atomic B factor: an ab initio calculation

The calculation of the mean-square atomic displacements (B factors) implemented in the open source code thermo_pw is presented. The B factors can be computed within the harmonic or the quasi-harmonic approximation for an arbitrary material with the accuracy of ab initio methods. A simplified calculation based on the Debye model is also implemented, where the only input ingredient is the Debye temperature which can also be calculated ab initio by the software. Applications to silicon and to the hexagonal close-packed metals Mg, Ru and Cd are presented.

Using a machine learning approach to determine the space group of a structure from the atomic pair distribution function

We present applications of machine learning models for predicting the space group of the underlying structure from its atomic pair distribution function (PDF).

Complex structural ordering of the oxygen deficiency in La_0.5Ca_2.5Mn₂O_7−δ Ruddlesden–Popper phases

New oxygen-deficient manganese Ruddlesden–Popper-related phases, La_0.5Ca_2.5Mn₂O_6.5 and La_0.5Ca_2.5Mn₂O_6.25, have been synthesized by controlled reduction of the fully oxidized n = 2 term La_0.5Ca_2.5Mn₂O₇. A complete structural and compositional characterization allows the proposition of a topotactic reduction pathway through preferential oxygen removal in the [MnO₂] layers along [031] directions.

Theoretical study of the properties of X-ray diffraction moiré fringes. I. Corrigenda and addenda

Seven corrections are made and several supplementary equations are added to the article by Yoshimura [Acta Cryst. (2015), A71, 368–381].

Quantum Field Theory Approach to Condensed Matter Physics

Dynamics of Solid Structures. Methods using Integrodifferential Relations