Faraday Discussion 135 took place at the University of Manchester from 4 - 6 September 2006. 

Many chemical concepts, e.g. hydrogen bonding, aromaticity and (hyper)conjugation, have been introduced at an intuitive level.  Some of these concepts are widely used in the primary chemical literature but their often vague and intuitive definition turns out to be the source of confusion and vigorous debate.  Extracting chemical information from modern wave functions and from experimental high-resolution electron densities is a challenging but most valuable task.

This Discussion was driven by the importance of bridging the expanding gap between widely used chemical concepts and modern accurate physical and computational data on molecules.  The meeting brought together the communities of scientists working in the areas of high-resolution crystallography, Valence Bond (VB) theory, Molecular Orbital theory, conceptual Density Functional Theory (DFT) and Quantum Chemical Topology (QCT).