Computational and experimental approaches to determining the structure and interaction potentials of prototypical biological systems

This paper presents an extensive survey of all previous experimental and high level theoretical predictions of binding energies and intermolecular distances for benzene: small molecule complexes, along with a brief overview of the techniques and methods used to obtain these data. Although equilibrium properties of these complexes are well within reach using high level theoretical methods that are currently available, obtaining agreement between experimental and theoretical values is harder, as quantum nuclear motion must be taken into account. A low cost alternative to conventional high level ab initio calculations is to express interaction potentials as classical expansions of the electrostatic, polarization, exchange-repulsion and dispersion energies, whose terms are derived from ab initio calculations of monomer properties. In this way, it is possible to obtain a global potential energy surface at a fraction of the computational cost associated with mapping out such a surface using high level ab initio calculations. This opens up the possibility of calculating quantum zero-point energies, vibrationally-averaged bond lengths and ro-vibrational excited state energy levels, to enable direct comparison of experimental and theoretical data.