Philip Bunker
Philip R. Bunker is a British-Canadian scientist and author, known for his work in theoretical chemistry and molecular spectroscopy. He is currently Researcher Emeritus at the National Research Council of Canada and a guest scientist at the Fritz Haber Institute of the Max Planck Society. Education and early work. Philip Bunker was educated at Battersea Grammar School in Streatham. He received a bachelor's degree at King's College in 1962 and earned a Ph.D. in theoretical chemistry from Cambridge University in 1965, advised by H.C. Longuet-Higgins. The subject of his Ph.D. thesis was the spectrum  of the dimethylacetylene molecule and its torsional barrier. During Bunker's Ph.D. work in 1963, Longuet-Higgins published his famous paper that introduced molecular symmetry groups consisting of feasible nuclear permutations and permutation-inversions. Under the guidance of Longuet-Higgins, Bunker applied these new symmetry ideas and introduced the notations G and G for the molecular symmetry groups of dimethylacetylene and ferrocene, respectively. After obtaining his Ph.D. degree, he was a postdoctoral fellow with Jon T. Hougen in the spectroscopy group of Gerhard Herzberg at the National Research Council of Canada. He then spent his entire career at the National  Research Council of Canada, eventually rising to the position of Principal Research Officer in 1997. Career and important contributions. Philip Bunker has published 180 refereed journal articles and 17 book chapters focused on the use of fundamental quantum mechanics to predict and interpret the spectral properties of polyatomic molecules due to their combined rotational, vibrational, electronic and nuclear-spin states, and their symmetries. He has been particularly concerned with the study of the energy levels and spectra of molecules that undergo large amplitude vibrational motions for which the Hougen-Bunker-Johns (HBJ) Hamiltonian was developed. Application of the HBJ Hamiltonian  to the methylene (CH) molecule has been particularly important in determining the separation between the singlet and triplet electronic states, and in determining which singlet and triplet rotational levels interact. In the 1990's, he returned to the problem of determining the torsional barrier in dimethylacetylene after Robert McKellar and John Johns, experimentalists at the National Research Council of Canada, had obtained a very high resolution infrared spectrum of the molecule. Analysis of its spectrum leads to a determination that the torsional barrier is only 6 cm (1.2 J or 72 J mol). Bunker is a well-known expert in  using the molecular symmetry group. At the end of Longuet-Higgins' paper in which he introduced permutation and permutation-inversion molecular symmetry groups, Longuet-Higgins wrote: "In conclusion it should be added that the present definition can be extended to linear molecules, and to molecules where spin-orbit coupling is strong; but these topics are best dealt with separately." However, Longuet-Higgins left the field of theoretical chemistry in 1967; he wrote nothing more about molecular symmetry and did not make these extensions. Extensions of these principles were subsequently made to linear molecules (Bunker and Papousek) as well as to  molecules with strong spin-orbit coupling (Bunker) Together with Per Jensen, a theoretical chemist at Bergische Universität Wuppertal, Bunker has written two books on theoretical chemistry and molecular spectroscopy; "Fundamentals of Molecular Symmetry" (2005) and "Molecular Symmetry and Spectroscopy" (1998). He is also well known for his work in the quantitative description of non-adiabatic effects in quantum molecular dynamics. Currently, Bunker is Researcher Emeritus at the NRC and a guest scientist at the Fritz-Haber Institute of the Max Planck Society. He has also held numerous visiting scientist positions at universities and institutions around the world during the course  of his career, including ETH-Zurich, Massey University, Kyushu University and University of Florence. Awards and honors. Bunker received the Humboldt Prize (1995), the Ionnes Marcus Marci Medal of the Czech Spectroscopy Society (2002), and the 2002 Sir Harold Thompson Memorial Award, which is sponsored by Pergamon Press (now Elsevier) for the most significant advance in spectroscopy published in Spectrochimica Acta each year. He is a fellow of the International Union of Pure and Applied Chemistry. During the course of his career he has delivered over 400 invited lectures.