The Nobel Prize in Chemistry 2013

Arieh Warshel, together with Michael Levitt and Martin Karplus, received the Nobel Prize in chemistry in 2013 for the Development of Multiscale Models for Complex Chemical Systems. On this page you find a short summary on the award and some scientific background, while we would like to encourage you to study our list of publications to gain deeper understanding and refer to the original information provided on the official web site of the Nobel Prize as well as references therein.
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Multiscale models for Complex Chemical Systems

The rapid developments in biochemistry over the last 50 years are perhaps the most striking. These were mainly enabled through the large efforts spent on the analysis of protein structures through X-ray crystallography or by analyzing the spin-spin couplings obtained from NMR-spectroscopy. What is perhaps less well known is the fact that computer programs are used to dissect the diffraction pattern from an X-ray investigation or the spin-spin couplings obtained from NMR experiments. These approaches apply computer algorithms aiming to calculate the energies of the considered structures based on empirically and theoretically obtained potentials that describe the interaction between the atoms in the system. This is mainly due the fact that experimental information to uniquely determine the structure of the studied system is limited. However, this is merely one of the aspects of how computers and theoretical models have become essential tools for the experimental chemist nowadays.

Therefore, questions on how complex chemical system may look like have nowadays slowly been replaced by questions on how these systems actually work. However, questions about the function are generally difficult to answer using experimental techniques, and, although methods such as isotope labelling and femtosecond spectroscopy can give clues, they rarely produce conclusive evidence for a given mechanism in systems with the complexity characterizing almost all biochemical processes (and of course most chemical processes). Here, the theoretical modelling has paved its way as an important tool as a complement to the experiment. Most importantly, chemical processes are characterized by transition states, and by configurations with the lowest possible (free) energy that links the product(s) with the reactant(s). To determine accurately the transition state is usually not experimentally accessible, while theoretical methods to search for such structures and consequently complement the experiment theoretically exist.

The work awarded this year´s Nobel Prize in Chemistry focuses on the development of methods using both classical and quantum mechanical theory which are used to model large complex chemical systems and reactions. Despite the obvious difference in the characterization of a system using quantum chemical models or by simpler classical models, this year´s laureates have developed methods that describe part of a system using first principle, quantum chemical models for a central part of the system and how to link this part to a surrounding, which is modelled using classical particles (atoms or group of atoms, i.e. coarse-grained methods). One of the key accomplishment was to show how the two regions in the modelled system can be constructed on a computer to interact in a physically meaningful way.

The prerequisites necessary for the development of these hybrid methods gave rise to a number of Nobel Prizes. Most notably, Walter Kohn and John Pople (1998), Max Planck (1918), Niels Bohr (1922), Prince de Broglie (1929), Werner Heisenberg (1932) and Erwin Schroedinger together with Paul Dirac (1933).