Thanks everybody who responded to my initial blog and follow ups. You're all great and have helped to focus my thoughts.
Since I was looking for more scientific "beef" about the subject I turned to university web pages.
Good stuff there. Still several questions left which I will take up with the authors.
If you're interested, here are some interesting sites that I found in a quick search.
http://web.mit.edu/chemistry/deutch/...arsNow2004.pdf,
http://greet.anl.gov/publications.html