Atom-atom potentials from ab initio calculations

Recent developments in ab initio intermolecular perturbation theory, using density functional theory, have made it possible to calculate intermolecular interactions between organic molecules of 30 or more atoms routinely and accurately. Related methods can provide accurate distributed properties of such molecules (multipoles and polarizabilitics). These developments open up new possibilities for accurate ab initio atom-atom potentials, at a time when applications have raised new challenges, in that aspects of the interaction energy that were once ignored must now be accounted for. This review seeks to show how modern ab initio methods in intermolecular perturbation theory, and new methods for distributing molecular response properties, can be used to develop a new generation of atom-atom potentials.