Quantum transition state theory for the collinear H+H-2 reaction

The recently formulated quantum transition state theory (QTST) in which the quantum projection operator is approximated by its parabolic barrier limit and the symmetrized thermal flux is evaluated numerically exactly, is appl ied to the collinear hydrogen exchange reaction. The results are found to b ound the exact results from above for temperatures ranging from T = 200 K t o T = 1000 K. The QTST rate is almost exact at high temperature and is a fa ctor of 3.7 greater than the exact rate at T = 200 K, where there is extens ive tunneling. Contour plots of the quantum transition state theory reactiv e flux reveal that the theory accounts well for the "corner cutting" observ ed in the collinear hydrogen exchange reaction at low temperatures. These r esults demonstrate that one may estimate quantum rates of bimolecular react ions, using only thermodynamic information.