Obituary for Rudolf Zahradník (1928–2020): “To Do What’s Right”

Abstract

Rudolf Zahradník, a pioneer of quantum chemistry and the founding president of the Academy of Sciences (1993) and the Learned Society (1994) of the Czech Republic, died on October 31 in Prague. Among his many distinctions were memberships in the International Academy of Quantum Molecular Science as well as Academia Europaea. In his autobiography (2008), Rudolf provided brief characterizations of a host of colleagues from the national and international community he respected and was fond of. Among their traits that he valued the most were determination, decency, kindness, noblesse—and a dose of connoisseurship, enhanced by the ability to tell stories. A harmonious combination of these very virtues is what aptly characterizes the personality of Rudolf himself. No wonder, then, that many of the like-minded in his surroundings looked up to him for leadership. By the time of the Velvet Revolution, in 1989, Rudolf was ready for high office both in academia and in government: while the former materialized abundantly, the latter—the state presidency—did not, to the detriment of his country. Rudolf’s scientific career started in the kitchen of his parents’ apartment in Prague—with an explosion (potassium chlorate with sulfur). He was about thirteen then. Instead of banning their only son’s further such activities, Rudolf’s parents merely banished them to a more suitable room within their apartment. As he would later reveal, the search for a “universal catalyst” was among Rudolf’s preoccupations, apart from his adventures as a dedicated Boy Scout. After the war—and the end of the Nazi occupation—he studied chemistry at a vocational high school and, in 1948–1952, at Prague’s Institute of Chemical Technology. Among his notable teachers at the Institute were Otto Wichterle (inorganic chemistry) and Jaroslav Koutecký (classical theoretical physics). In the final semester, Rudolf started, on his own, reading up on quantum mechanics—in The Theory of Rate Processes by S. Glasston, K. Laidler, and H. Eyring. Thus, on the subject to which he would dedicate much of his career, he was, in his own words, an autodidact. However, the Institute offered a course in higher mathematics (calculus and linear algebra), a rarity in the chemistry curricula at the time, which Rudolf took full advantage of. However, it was also at his alma mater that he heard for the first time the snub that “quantum mechanics may be good for the study of the hydrogen atom—but that’s not chemistry.” It was at the Institute for Occupational Medicine led by the polymath Jaroslav Teisinger that Rudolf made his first contributions to quantum chemistry. By using Hückel’s theory of molecular orbitals (HMO), he found new organizing principles concerning the toxicity of aliphatic compounds and the stability of sulfur heterocycles. A successful search for correlations between the electronic spectra of conjugated systems and their HOMO–LUMO energy gaps obtained via HMO was among Rudolf’s other pioneering feats. Apart from paper and pencil, the technology he used was a borrowed Olivetti calculator. Charles Coulson’s plea to theorists * Bretislav Friedrich [email protected]