## PHYS 439 |

The Herman-Kluk (HK) semiclassical approximation for the propagator has enabled dynamical and spectroscopic calculations for relatively large molecules and condensed phase systems. Although this treatment can be quite accurate, its limitations become apparent for systems exibiting substantial tunneling and over-barrier reflection. We have applied a recently-developed theory that corrects HK theory to higher order in Planck's constant. Calculations for test systems show that it indeed improves the accuracy of the HK treatment in a systematic way. Different computational strategies exist, including one that allows the calculation of higher-order corrections using about the same number of classical trajectories as for a conventional HK treatment. Analysis of the numerical results reveals how the convergence properties of the correction series and the accuracy of the HK treatment depend on the classical dynamics of the system for complex initial conditions. |

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster
Division of Physical Chemistry |