The Physics of Elementary Chemical Processes: Newton or Schrodinger (or is Chemistry Simpler than We Thought

McCaffery Anthony A.J.mccaffery@sussex.ac.uk University of Sussex, Brighton, UK  
Recent experimental and theoretical studies of atom-diatom collision indicate that even the most highly resolved observations obey a hybrid Newtonian-Schrödinger mechanics in which the molecular eigenstates provide constraints to classical or near classical trajectories. Vector relations through which momentum of relative motion is converted to internal momentum of the molecule or into recoil are obeyed and thus the incident trajectory is set by the threshold requirements of the product |v,j| > state.
 This allows the development of easily visualised physical models from which quantitative predictions of the outcome of collions may be predicted. Models are described for inelastic and reactive collisions which successfully predict |v,j| > distributions in the case of inelastic and reactive collisions. These vector conditions may be seen as an important component of the forces that determine stereochemistry in reactive encounters and incorporating such restrictions into the steric factor may lead to a re-evaluation of simple collision models of reaction rates.