He earned his master’s degree in 1966 with Milan Randić, with the thesis The method of maximum overlap and its application to the calculation of hybrids of some methyl-substituted cyclopropanes, and his PhD in 1967 with the dissertation The electronic structure of some polyatomic molecules at the Faculty of Science, University of Zagreb. The dissertation was prepared under the supervision of John N. Murrell FRS at the University of Sheffield and the University of Sussex (Brighton). These were the first master’s thesis and the first doctoral dissertation in the field of quantum chemistry in Croatia.
He spent his postdoctoral training at the Department of Chemistry, University of Texas at Austin (1968–1970), working with Michael J. S. Dewar FRS. After graduation, he worked for a year and a half at the Pliva Research Institute (1960–1962), and on March 1, 1962, he joined the Ruđer Bošković Institute at the invitation of his friend Krešimir Humski, in the Laboratory for Physical Organic Chemistry led by Dionis Emerik Sunko. In mid-1966, he moved to the Theoretical Chemistry Group in the Division of Physical Chemistry, led by Randić. At the Institute, he served as trainee (1962), research assistant (1963), research associate (1967), senior research associate (1971), and research advisor (from 1977, re-elected in 1998). At the same time, he taught at the Faculty of Science as Assistant Professor (1970), Associate Professor (1973), Full Professor (1977), and from 1998 as Full Professor Emeritus. He retired in 2001 and in 2005 was awarded the title of Distinguished Scientist of the Ruđer Bošković Institute.
He published more than 550 scientific papers, several hundred review and professional articles, and 12 books. He is the author of the first book on chemical graph theory, Chemical Graph Theory (CRC Press, Boca Raton, 1983, second edition 1992). The book has been highly cited, with more than 2,200 citations. Two of his books were in press: Croatian Chemistry in the 20th Century – People and Events (Školska knjiga and HAZU) and Life in Science (HAZU). He was among the most cited Croatian chemists, with an h-index of 52.
His research focused on the development and application of quantum chemical, computational, and mathematical methods in chemistry, as well as on people and events in Croatian chemistry. In quantum chemistry, he worked on the development of MO and VB theories applicable to large molecules. In mathematical chemistry, he worked on the development and application of chemical graph theory. Many authors consider the paper A. Graovac, I. Gutman, N. Trinajstić, T. Živković, Graph Theory and Molecular Orbitals. Application of Sachs Theorem, Theoret. Chim. Acta 26, 67–78 (1972), as the beginning of modern chemical graph theory.
In computational chemistry, in collaboration with colleagues from the University of Düsseldorf, he worked on the development of algorithms for the characterization, generation, and enumeration of chemical structures (for example, Computational Chemical Graph Theory: Characterization, Enumeration and Generation of Chemical Structures by Computer Methods).
His most cited paper was Graph Theory and Molecular Orbitals. XIX. Non-Parametric Resonance Energies of Arbitrary Conjugated Systems (507 citations up to early 2014), in which he proposed a new approach to calculating resonance energy as a measure of the aromaticity of conjugated molecules. He also authored two books on Croatian science and chemists: Essays on Science and Scientists, Matica hrvatska, Zagreb, 1998, and 100 Croatian Chemists, Školska knjiga, Zagreb, 2002.
From 1990 to 1993 he was Co-Editor-in-Chief of the Journal of Mathematical Chemistry, from 1994 to 2005 Editor-in-Chief of Croatica Chemica Acta, and from 2001 to 2008 Editor-in-Chief, and since 2009 Honorary Editor, of Prirodoslovlje, published by Matica hrvatska.
He was a member of numerous scientific and cultural societies and associations, such as Matica hrvatska since 1955, the Croatian Chemical Society since 1960, the Croatian PEN Center since 1987, and the Brethren of the Croatian Dragon since 1991 (with the dragon name Zmaj Primorski). Since 1992 he had been a full member of the Croatian Academy of Sciences and Arts, and since 2005 a member of the International Academy of Mathematical Chemistry.
He received many awards, including the City of Zagreb Award (1972), the Republic Award for Science Ruđer Bošković (1982), the American Mid-America State Universities Association Distinguished Foreign Scholar Award (1986), the State Award for Lifetime Achievement (2004), and the Božo Težak Medal (2005).
Several journals dedicated special issues to him: Internet Electronic Journal of Molecular Design (2003/2004), Croatica Chemica Acta (2004), Journal of Chemical Information and Computer Sciences (2007), and International Journal of Chemical Modelling (2014).
