Classical Crystallography Research Articles

Generalised crystallography

Classical crystallography consists of the study of those atomic assemblies which can be generated by the function GROUP (MOTIF) ⇒ PATTERN. We are now concerned with the more general pattern-generating function: PROGRAM (MOTIF) ⇒ STRUCTURE, which requires us to look into the concept of INFORMATION in which the PROGRAM is written. Some structures may contain their own PROGRAMS where the information is represented as a material structure. Inorganic and living matter are part of a continuous spectrum of organisation. We present the outlines of a philosophy of structuration or structuralism based on the scientific rather than on the literary culture. A crystal lacks rhythm from excess of pattern, while a fog is unrhythmic in that it exhibits a patternless confusion of detail The difference between a piece of stone and an atom is that an atom is highly organised, whereas a stone is not. The atom is a pattern, and the molecule is a pattern, and the crystal is a pattern; but the stone, although it is made up of these patterns, is just a mere confusion. It's only when life appears that you begin to get organisation on a larger scale. Life takes the atoms and molecules and crystals, but, instead of making a mess of them like the stone, it combines them into new and more elaborate patterns of its own. Those reductionists who try to reduce life to physics usually try to reduce it to primitive physics—not to good physics. Good physics is broad enough to contain life, to encompass life in its description since good physics allows a vast field of possible descriptions.

Crystallography and the penrose pattern

The Penrose pattern is a tiling of two-dimensional and of three-dimensional space by identical tiles of two kinds (acute and obtuse rhombi with α = 72° and 144° in two dimensions and acute and obtuse rhombohedra with α = 63.43° and 116.57° in three dimensions). The two-dimensional pattern is a section through that in three dimensions. When joining (or recursion) rules are prescribed, the pattern is unique and non-periodic. It has local five-fold axes and thus represents a structure outside the formalism of classical crystallography and might be designated a quasi-lattice.

An Introduction to Crystallography (4th Edn)

This excellent text is still probably the best introduction to classical crystallography on the market, a fact made abundantly clear by the appearance of the fourth edition. First published in 1946 and now in paperback form one's first impression compared with previous editions is that the text is enhanced by the larger and clearer diagrams together with improvement in general layout.

Crystals

THE CONCERN of modern crystallography is with the atomic theory of matter in all states of aggregation and with the optical principles of the diffraction of short‐wavelength radiation by such matter. This broad definition is a far cry from the morphological emphasis of early classical crystallography; it is, however, just a logical extension of concepts initiated by Max von Laue's demonstration in 1912 of x‐ray diffraction by crystals. Not only can the physical properties of a crystal be interesting; they can also be esthetically pleasing (figure 1).

Sir William Pope, K.B.E., F.R.S.

WILLIAM JACKSON POPE, the great chemist, was the eldest son of William and Alice Pope who at the time of his birth (March 31, 1870) lived in New North Road in the City of London. On leaving the Cowper Street Endowed School, Pope proceeded to the Finsbury Technical College, where he was one of H. E. Armstrong's earliest pupils. He followed Armstrong to the Central Institution (now the City and Guilds’ College of the Imperial College of Science and Technology), where the scheme of scientific studies having no reference to outside examining bodies did not lead to a university degree but gave Pope a rigorous training in chemistry, classical crystallography (under H. A. Miers) and in research methods admirably suited to his genius. From that time dated the unique friendship between Armstrong and Pope which was only broken by the former's death in 1937.