QUANTUM DYNAMICS STUDY OF LI+HF REACTION

We report rigorous quantum dynamics studies of the Li+HF reaction usin g the time-dependent wavepacket approach. The dynamics study is carrie d out on a recent ab initio potential energy surface, and state-select ed reaction probabilities and cross sections are calculated up to 0.4 eV of collision energy. Many long-lived resonances (as long as 10 ps) at low collision energies (below 0.1 eV) are uncovered from the dynami cs calculation. These long-lived resonances play a dominant role in th e title reaction at low collision energies (below 0.1 eV). At higher e nergies, the direct reaction process becomes very important. The react ion probabilities from even rotational states exhibit a different ener gy dependence than those from odd rotational states. Our calculated in tegral cross section exhibits a broad maximum near the collision energ y of 0.26 eV with small oscillations superimposed on the broad envelop e which is reminiscent of the underlying resonance structures in react ion probabilities. The energy dependence of the present CS cross secti on is qualitatively different from the simple J-shifting approximation , in which a monotonic increase of cross section with collision energy was obtained.