Average Chemist Research Articles

Just how good is DFT?

Density functional theory (DFT) has become a ‘‘household tool,’’ so to speak, for the average chemist. We now take it for granted: we expect DFT to provide a reasonably good description of almost any molecule we can make—or rather, we can think of—and justifiably so. For organic molecules, this is a perfectly valid expectation. However, for transition metal complexes and transition states, the performance of DFT, while generally very good, is less certain, while van der Waals complexes are largely beyond the range of applicability of current DFT methods. Given DFT’s broad and increasing popularity among bioinorganic chemists, a need has been felt for a critical evaluation of the performance of DFT, from a bioinorganic perspective. This series of four Commentaries is intended to address that need. Modern DFT began in 1964, with a famous paper by Hohenberg and Kohn [1] which contained the following two rigorous theoretical results. First, the groundstate electron density uniquely determines the electronic wavefunction and hence all ground-state properties of an electronic system. Second, the energy of an electron distribution is a function—more technically, a functional—of the electron density and this functional is a minimum for ground-state densities. The Hohenberg–Kohn theorem assures us that the density functional is a universal quantity, but it does not specify its form. These results reduce the problem

The Fourier transform in chemistry—NMR: Part 3. Multiple-pulse experiments

This paper will provide the average chemist with an introduction to the information that can be gained from Fourier transform in chemistry.

UNRAVELING EXAFS SPECTROSCOPY

The past several years have witnessed the emergence of Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy from an esoteric technique to a widely available structural spectroscopic tool. Several in-depth review articles and books are available on the subject, but some aspects of theory or data reduction may be beyond the scope or need of the average chemist. In this article the authors will try to reduce the mystique surrounding EXAFS and clarify the terminology and concepts in the EXAFS literature. They will concentrate primarily on theory and data analysis and conclude with a few applications.

OTS Translation Clearinghouse

WHEN the Allies emerged victorious over Germany, they agreed among themselves that the technical advancements made by German science and industry were a world asset which could be rightfully distributed by the conquerors. Foremost among the technology in which Germany was pre-eminent was chemistry, it is in this field, particularly, that an enormous wealth of new material has been uncovered by the investigators of the allied powers. Chemical Discoveries German advances in the fields of dyes, plastics, acetylene chemistry, military chemicals, rubber chemistry, synthetic petroleum, and others have been found to be such as to make the average chemist's mouth water. This does not mean, necessarily, that the Germans were ahead of us in their total chemical investigations, but it does mean that they had explored sectors of chemistry to which we in America had paid relatively little attention, and that these explorations have opened up for our industry many new fields of developments. Among ...

Magnetochemie

BY magnetochemistry is meant the examination of the problems of chemical structure in the light of magnetic measurements and modern magnetic theory, and it is clear that the author of this book has thoroughly studied the more important methods of susceptibility determinations and the theoretical significance of the results. He does not assume that his readers already know all about the matters on which he writes, and his work is a fine example of careful exposition based upon a proper attention to fundamental conceptions and definitions. The outline of experimental methods and technique is by no means exhaustive, but it should be adequate for the average chemist who is likely to read the book. Magnetochemie Von Prof. Dr. W. Klemm. (Physik und Chemie und ihre Anwendungen in Einzeldarstellungen, Band 1.) Pp. xv + 262. (Leipzig: Akademische Verlags-gesellschaft m.b.H., 1936.) 18 gold marks.

Essai de philosophie chimique

PROF. DELACRE of Ghent is in revolt against modern theories. In a “Profession of Faith “which forms the first section of his introduction, he asserts that “Every principle, every a priori conception, every theory, every system, however brilliant it may be, however fertile it may appear, is only an illusion.” He questions even the usefulness of theories, on the ground that they have in the past often provided obstructions to the progress of new ideas, and quotes with approval the view that, if one makes use of theories, one should do so, in-the words of St. Claire Deville, “without believing them.” He appears to have reached this almost morbid point of view as a result of having devoted much time to the study of the pinacone-pinacoline transformation, one of the curious changes which (like the Walden inversion) have never yet found a clear interpretation on the basis of conventional views of atomic linking and molecular structure; but, whereas the average chemist (fortunately) is stimulated by such anomalies, and is always hopeful of finding some clue to the mystery which they conceal, Prof. Delacre prefers to “throw up the sponge “and to denounce all theories as useless frauds. Sir Joseph Thomson has recently stated that “A theory is a tool and not a creed “; this is at least a more cheerful and practical view than the exercise in which Prof. Delacre indulges of finding fault with tools in general, and especially with those of his own trade. They may not be perfect, but they are certainly not useless.

A German-English Dictionary for Chemists

DR. PATTERSON has filled what has long been an irritating lacuna in the average chemist's library. Certain scientific and technical terms are by no means easy to translate from the German, and recourse to the dictionary usually available is generally hopeless. The book under review should therefore be eagerly welcomed by the steadily increasing number of young chemists in England and America and by those who, even if they have already a good working knowledge of the language, are occasionally at fault. Not only is it a good general dictionary of the German language, but it contains also a very complete collection of chemical terms belonging both to the pure science and to technology.