Quantum Chemistry: Classic Scientific Papers Hinne Hettema World Scientific, River Edge, N.J., 2000. $90.00 (478pp.). ISBN 981-02-2771-X
Hinne Hettema’s Quantum Chemistry is a finely produced, useful, and highly thought-provoking book. Hettema is a chemist turned philosopher, and he has credentials in both disciplines.
The body of the book consists of 26 German-language papers by 18 authors, written between 1926 and 1934, all expertly translated into English. Of the papers, 21 are from the journal Zeitshrift für Physik. Given the importance of these papers, teachers of quantum chemistry or molecular physics well might require their students to read this book at the time they are treating the theory of molecules and molecular spectra. What more valuable experience could there be than to study the magnificent paper by Max Born and J. Robert Oppenheimer, or several of the astounding papers of Fritz London, or those of Friedrich Hund, Egil Hylleraas, John Charles Polanyi, or Eugene Wigner? By 1934, there were many classic papers in English as well as in German, and so “Classic German Scientific Papers” would have been a better subtitle for the book.
At the start of the book is a provoking 23-page essay by Hettema entitled “Philosophical and Historical Introduction.” This includes an analysis of the shift of the center of research in quantum chemistry away from Germany and to the English-speaking countries. The author concludes that “the smooth transition of quantum chemistry to the USA, as it took place in the 1930s, had to do with the embedding of the quantum chemistry community in the wider environment in Weimar Germany, and the manner in which the applications of quantum mechanics were ill-suited to the Weimar intellectual environment.”
To the contrary, I would rather claim that this transition was due quite simply to the Gilbert N. Lewis–Linus Pauling tradition in the US, plus the distinguished leadership, through the transition period in the English-speaking countries, of Robert Mulliken, John Slater, John Van Vleck, Henry Eyring, John Lennard-Jones (England), and Gerhard Herzberg (Canada). Of these, only Herzberg was an immigrant, although other immigrants played central roles. In particular, one should mention Maria Goeppert-Mayer, whose 1938 paper (with Alfred Sklar) in the Journal of Chemical Physics was her only contribution to quantum chemistry but perhaps was the most farsighted electronic-structure paper before World War II. Karl Herzfeld also made important contributions (of which few people know).
When I began research in the 1940s, superior English sources were available to me. There was the wonderful review on valence theory by Van Vleck and Albert Sherman in Reviews of Modern Physics (1935) volume 7, page 167, a little book by W. G. Penney The Quantum Theory of Valence (Methuen, 1935), the text Introduction to Quantum Mechanics (McGraw-Hill, 1935) by Pauling and E. Bright Wilson, and the monograph by Pauling, The Nature of the Chemical Bond (Cornell, 1942). Most important, because it did not eschew mathematics and was up to date, was the great text Quantum Chemistry (Wiley, 1944) by Henry Eyring, John Walter, and George Kimball. The masterpieces by Herzberg on atomic and molecular spectroscopy were important because understanding of spectra was a primary goal. I felt no need to consult German sources, save for Wigner’s Gruppentheorie (Vieweg, 1931). I note in passing, however, that German quantum chemistry became world-class both in quality and quantity by the 1950s.
Hettema states that relations between the physics and chemistry communities have been important in the evolution of quantum chemistry. True! These relations have been particularly supportive of quantum chemistry in the US. Several pioneers from the old days, notably Mulliken (trained as a chemist but professor of physics for most of his career), Slater (physicist), and Lennard-Jones (theoretical chemist) maintained positions of strong leadership through their individual publications as well as schools they established. Theoreticians from all over the world—physicists and chemists alike—flocked to their laboratories, and there soon existed a worldwide network of lifelong friends with common interests. Harold Urey and Joe Mayer in 1932 established the Journal of Chemical Physics , which has remained unrivaled. Mulliken led the formation of the division of chemical physics of the American Physical Society. And the educational system quickly responded, with the whole chemical professoriate in the US recognizing that the chemistry undergraduate curriculum should be strong in physical chemistry and should include substantial mathematics and physics.
There is, however a barrier between physics and chemistry, illustrated well by the differences between molecules as viewed by Lewis and as treated in the 26 papers in Hettema’s collection. On the one hand (physics), one has a quantum-mechanical many-body problem to be solved; on the other hand (chemistry), there is the vast universe of molecular fact and reigning old chemical theories. Bonds exist and are often transferable; molecules have functional groups that are much the same from molecule to molecule; molecules are composed of atoms, but these atoms are not trivially the same as the atoms of atomic physics.
So, there is the Schrödinger equation, yes; but to achieve full understanding, the molecular theory must be developed carefully, mixing in extensive, quantitative, variegated chemical knowledge. In my opinion, the quantum chemistry of today has been driven not just by solution of the molecular Schrödinger equation begun by the 26 papers in the Hettema collection. It is a more complex subject, born out of decades of work by physical organic chemists, physical inorganic chemists, computational chemists, and theoreticians, effectively interacting.
