MAKING USE OF HOW QUICKLY ELECTRONS MOVE IN MOLECULES

In spite of the pioneering work of Coulson and co-workers in the 1940' s, little attention has been paid to electron momentum distributions. Lack of familiarity to chemists has meant that relatively little work has been done to extract information of chemical interest from momentu m densities. In this paper we have discussed the form of momentum-spac e densities for simple systems and we have described applications to m olecular similarity. Momentum-space similarity indices tend to be espe cially useful when the bonding topology is less important than the lon g range valence electron density. Opportunities such as those provided by momentum space for chemists to view electrons in molecules from a new perspective are rare and deserve careful study.