University of Sydney
I am primarily a theoretician, but also engage with relevant experiment. A long-standing interest has been in electron (or more generally, charge) transferin chemical systems, The kinetics of simple isotopic exchange reactions such as Fe*2+ / Fe3+ can be understood in terms of diabatic energy surfaces generated through electron-vibrational interaction (lambda) coupled through electronic interaction (J )to produce Born-Oppenheimer adiabatic surfaces. This two-site model for the ground state can be generalized to describe any donor-acceptor charge transfer. The vibronic coupling lambda can be to any number of internal modes (e.g. 100 in the bacterial photosynthetic radical cation) and medium (solution or crystal) modes. In the more general case where donor and acceptor are different species, there is an overall energy offset Eo to consider. In general, an optical transition to the upper adiabatic surface ( 'intervalence transfer') is allowed (giving rise to typical strong colours of mixed-valence systems) permitting values of the parameters lambda (and its individual contributions)) J and Eo to be deduced. Where donor and acceptor are linked through a bridging molecule, electronic properties depend critically on the ratio of J to lambda/2 , ranging from kinetically localized to single- minimum maximally quantum-entangled delocalized in the case of molecules, and from charge density wave through spin density wave to metallic behaviour in the solid state as the ratio approaches or surpasses unity. This coupled diabatic approach links in, for example, with general theories of chemical reaction dynamics, proton transfer, aromaticity and umbrella-type inversion (e.g. in ammonia). This work has progressed naturally to Molecular Electronics, where conduction through molecular wires linked to nanoelectrodes, principally ballistic but modulated by vibronic coupling, is considered. The dependence of conductivity and quantum interference effects on the structure of the molecular wire and details of links to the metal interfaces raise analogous problems. In this work, detailed quantum chemical calculations are needed, particularly to interpret Scanning Tunnelling Microscope and allied images. This connects with my long-standing interest in calculation of molecular properties, particularly response functions such as electronic and vibrational Stark effects.
论文共 160 篇作者统计合作学者相似作者