Tags: Coulson Lecture

Systems of chemical reactions are central to a wide range of technological and environmental questions, such as autoignition in combustion engines, heterogeneous catalysis, or formation of atmospheric aerosols. Understanding the details of these systems requires knowledge of not only the individual reaction steps but also the way these steps interact in the web of chemical transformations.  At the Combustion Research Facility (CRF) at…

How non-covalent interactions contribute to gas-phase bond energies. What is the design behind Vitamin B12? Homolytic dissociation of the weak Co-C bond in Vitamin B12 (adenosylcobalamine), an essential cofactor in a large number of enzymes, initiates radical reactions.  Modulation of the bond dissociation energy is accordingly a key element in control of enzymatic activity, although one would ordinarily consider homolytic bond…

In this talk, I will discuss recent work in our group in which we made connections between proton transfer processes and hydrogen bonding and vibrational frequencies and intensities.  Due to the large amplitude motions associated with proton transfer along a hydrogen bond, the vibrational spectra of these systems contain features that cannot be understood by the usual harmonic description of molecular vibrations, and even the widths of…

I will report our latest developments of multireference methods with special focus on multiconfiguration pair-density functional theory (MC-PDFT) [1] and its application to understanding the properties and reactivity of electronically excited states [2] and transition metal-containing systems.[3] MC-PDFT combines mutireference wave functions and density functional theory methods to treat strongly correlated systems. I will illustrate examples of…

Symmetry with respect to space inversion was assumed to be fundamental in the theory of chemical bonding at the time of Coulson’s ‘Valence’ and in quantum chemistry and stereochemistry in general for decades thereafter. Symmetry and asymmetry are concepts, which are, indeed, used in a wide range of contexts, from the  fundamental sciences, mathematics, physics, chemistry and biology to the arts, music and architecture [1]. We shall start…

Activation processes have been studied in many different contexts, in this lecture we will discuss two essential aspects: energetic and electronic. Among many theoretical models intended to rationalize chemical processes and the energies involved, the Marcus equation is one of the most successful analytic forms that provides nice ways to rationalize the activation energy and to characterize the transition state through the Hammond postulate and…