Semiquantal analysis of adiabatic hydrogen transfer rate.

The reaction rate of adiabatic proton/hydrogen/hydride (H) transfers in condensed phase is examined by combining the semiquantal time-dependent Hartree theory and the multidimensional transition state theory, which takes into account the zero-point effect and the dynamical modulation of the wavepacket width in the adiabatic transfer regime. By applying the theory to a model potential consisting of a quartic double well coupled linearly and quadratically (symmetrically) to external degrees of freedom, a set of compact analytical formulas was derived for the adiabatic H transfer rate. The analysis suggests that the kinetic isotope effect on the H transfer rate may exhibit a maximum as a function of the coupling strength to the external degrees of freedom measured by the reorganization energy.