Combining two kinds of computer calculation means chemists can accurately model reactions like hydrocarbon cracking.

Density functional theory (DFT) is one of the most popular and versatile methods in computational chemistry. Chemists use it to investigate the electronic structure of systems containing large numbers of molecules.  But DFT falls down when it comes to modelling weak intermolecular interactions such as van der Waals forces.  Reactions of small organic molecules within the binding pocket of an enzyme or the pore of a solid catalyst involve van der Waals interactions and have proven difficult to describe using DFT.

Joachim Sauer and Christian Tuma at the Humboldt University, Berlin, Germany, have proposed a neat solution to this problem.  Sauer and Tuma combined DFT with a calculation method known as Møller-Plesset perturbation theory (MP2).  Although MP2 calculations are too time consuming to be used on large chemical systems, such as the pore of a zeolite, they do describe van der Waals forces very well.

Sauer and Tuma's method combines the strengths of DFT and MP2 to give an accurate method for modelling hydrocarbon cracking - breaking large hydrocarbon molecules into smaller, more useful ones, using zeolite catalysts. 

Richard Catlow, director of the Davy Faraday Research Laboratory at the Royal Institution, London, UK, said the method could find a broad range of applications. Catlow described the work as 'ingenious' and 'a most significant development in computational chemistry.' 

Colin Batchelor