1. Could you explain the significance of your article to the non-specialist? 

Many chemical physicists work at including quantum mechanical ingredients in classical mechanics in order to improve its ability to describe nuclear motions in chemical reactions. Classical mechanics is indeed more intuitive, much easier to use and applicable to much larger molecular systems than quantum mechanics. Our paper is a contribution to this research in the particular framework of gasphase bimolecular reactions. 

2. What has motivated you to conduct this work? 

Differential cross sections (DCSs) are major observables providing information about the spatial distribution of the products of bimolecular collisions. In the case of complex-forming processes, recent studies showed that classical mechanics reproduces very well the quantum DCSs, apart from sharp forward/backward peaks. This was an intriguing finding which we have tried to understand. 

3. Where do you see this work developing in the future? 

For the time being, our analysis is limited to complex-forming reactions. It should be thus extended to direct processes but the problem seems to be more complex. 

4. Are there any particular challenges facing future research in this area? 

As shown, for instance, by K. Liu, A. Suits and coworkers (PCCP Hot papers of June 2006), experiments on the dynamics of chemical reactions are reaching an amazing level of sophistication. In addition to that, the molecular systems of interest nowadays tend to increase in size. There is thus an urgent need for accurate and efficient theoretical approaches, possibly combining astutely classical and quantum mechanics.