CROSS-SECTIONS AND RATE CONSTANTS FOR THE F-]XF+X (X=H,D) REACTIONS -A 3-DIMENSIONAL QUANTUM-MECHANICAL CALCULATION(X(2)(V=0,J))

In this letter we report on quantum mechanical cross sections and rate constants for the title reactions as calculated on the 6SEC potential energy surface. The calculations, carried out in the reagents arrange ment channel employing negative imaginary potentials, were done within the coupled-state approximation. The calculated cross sections were c ompared with quasi-classical trajectory calculations and in the case o f F + H-2 also with (the four available) formally accurate quantum mec hanical ones. The most pronounced quantum effects were found in reacti ons with the diatom reagent in the j = 0 level, However, these effects were not large enough to cause a significant increase in the rate con stants as compared to those calculated by the QCT method even at very low temperatures. As for the F + D-2 reaction, the good agreement that was found earlier between quasi-classical rate constants and experime nt was kept in the current QM calculations.