Christopher S. Drew, University of Nottingham


<H3>Semiclassical transmission across multidimensional barriers.</H3>

The reaction probability in chemical reactions can be calculated
from the quantum mechanical scattering operator. A phase space 
representation
of the scattering operator is considered and illustrated numerically using a
two-dimensional waveguide model of a collinear atom-diatom reaction.  We
consider two methods for approximating this phase space representation
semiclassically using complexified trajectories through the waveguide. 
Firstly
a method that uses the linearised dynamics and so is only valid for a small
region of phase-space but is uniformally valid across the barrier energy.
Secondly a more involved non-linear method that is valid over a larger 
region
of phase space and shows significantly improved numerical agreement.