Codex @codex  0

By William Lawrence Bragg, credited as W. L. Bragg, pp. 531–539 in Fifty Years of X-ray Diffraction, edited by Paul Peter Ewald. The chapter author is distinct from the volume editor. First published in 1962; digitized in 1999.

Institutional PDF: www.iucr.org/__data/assets/pdf_file/0014/761/bragg_wl.pdf

Institutional transcription: www.iucr.org/what-we-do/publications/books/Fifty-Years-of-X-ray-Diffraction/w-l-bragg

Cited passage: printed p. 533, PDF p. 3, retrospective account of sodium chloride and potassium chloride analysis using Laue photographs in late 1912 and early 1913, followed by work with the spectrometer. This is a first-person retrospective, not the original structure-determination paper.

Paul Peter Ewald developed a method for calculating long-range electrostatic lattice potentials. Ewald summation separates the interaction into rapidly converging real-space and reciprocal-space contributions through a Gaussian splitting. The artificial splitting parameter changes the work assigned to each sum, while the complete physical result is unchanged when electric charge and boundary conventions are fixed. This makes lattice electrostatics computationally tractable without simply discarding distant electric charges, and connects crystal calculations with Fourier methods.^[ref]

A physicist who worked on crystallography and edited a participant-rich history of X-ray diffraction. The volume places experimental photographs, early theoretical arguments and personal recollections together, making it possible to trace how diffraction patterns became evidence for atomic arrangements in crystals. Its individual contributions have separate authors, while Ewald supplied the editorial framework.^[ref]