Ewald, Paul

A. Toukmaji and D. Paul and J. A. Board, Jr., Distributed Particle-Mesh Ewald A Parallel Ewald Summation Method, Proceedings, International Conference on Parallel and Distributed Processing Techniques and Applications (PDPTA 96), CSREA Press (1996), pp. 33-43. 

Bethe obtained his doctorate in 1928 summa cum laude and became Paul Ewald s assistant in Stuttgart. Ewald— wliose wife was the niece of a famous and influential reform rabbi—opened his home to the young Bethe and he became a frequent visitor. Ten years later he married Rose, one of Ella and Paul Ewald s daughters. After his brief stay in Stuttgart, Bethe returned to Munich to do his Habilitation tvith Sommerfeld. 

These examples show the great practical utility of the Ewald sphere construction. We did once hear Paul Ewald say, some sixty years after he laid the basis of X-ray scattering theory, that he wished people had named something else after him, as it was such a trivial idea ... 

Paul P. Ewald, 1888-1985. Physicist and crystallographer, professor at the Universities of Munich, Stuttgart, Queen s University at Belfast, and the Polytechnic Institute of Brooklyn. 

Peter Paul Ewald (1888-1985) uses reciprocal lattice vectors to interpret the diffraction patterns by orthorhombic crystals and later generalized the approach to any crystal class. 

The sums may be carried out with respect to the atomic positions in direct (real) space or to lattice planes in reciprocal space, an approach introduced in 1913 by Paul Peter Ewald (1888-1985), a doctoral student under Arnold Sommerfeld (Ewald, 1913). In reciprocal space, the structures of crystals are described using vectors that are defined as the reciprocals of the interplanar perpendicular distances between sets of lattice planes with Miller indices (hkl). In 1918, Erwin Rudolf Madelung (1881-1972) invoked both types of summations for calculating the electrostatic energy of NaCl (Madelung, 1918). 

Another useful mathematical image in reciprocal space is the sphere of reflection, introduced by Paul Ewald and named after him. The Ewald sphere (Figure 6(a)) has the diameter of 2/A, coinciding with the direction of the incident beam (wavelength A). The crystal (in direct space) is placed at the... 

Once it had been shown that crystals diffract X rays, the relationship between the observed effect and the experimental conditions was put on a sound mathematical basis by Max von Laue, Paul P. Ewald and many others.X-ray diffraction by crystals represents the interference between X rays scattered by the electrons in the various atoms at various locations within the unit cell. It must, however, be stressed again that any molecule or ion can diffract X rays or neutrons. It is only when this diffraction is reinforced by the repetition of the unit cell in the crystal that diffraction by atoms is a conveniently observable effect, for example as spots of differing intensity on photographic film. Of particular interest to chemists and biochemists is the work by W. L. Bragg,who demonstrated that measurement of the diffraction patterns gives information on the distribution of electron density in the unit cell, (i.e., the arrangement of atoms within this unit cell). 

Colella, R. Multiple diffraction of X-rays and the phase problem. In P. P. Ewatd and his Dynamical Theory of X-ray Diffraction. A memorial Volume for Paul P. Ewald. S3 January 1888 — SS August 1985. (Eds., Cruickshank, D. W.. 1 Juretschke, H. J., and Kato, N.) International Union of Crystallography/OxforJ University Press Oxford (1992). 

Peter Paul Ewald (1888-1985). German physicist, whose work [P.P. Ewald, Das reziproke Gitter in der Strukturtheorie, Z. Kristallogr. 56, 129 (1921)] is considered a landmark in using reciproeal lattice in x-ray diffraction. 

Max von Laue was a Privatdozent and Paul Peter Ewald was a doctoral student at the University of Munich in 1912 when Ewald told Laue about his thesis on crystal modek. In what he later called the bluest mistake of hk scientific fife, Ewald did not realize that the spacings between layers of hk model su ested the possibility of X-ray diffiaction, which Laue quickly went on to discover and prove. 

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