Dynamics of hydrogen atom and proton transfer reactions. Symmetric case

Abstract

A method is devised for treating the transfer of a light particle such as a hydrogen atom or a proton between two heavy particles, for the case of a collinear symmetric reaction AH+A-->A+HA. Polar coordinates (rho,theta) with origin at the origin of the usual mass-weighted skewed-angle potential energy contour plot are employed to simplify the calculation. Symmetric and antisymmetric vibrationally adiabatic states are obtained at each rho. They provide an effective potential for the rho motion and are used to obtain the elastic adiabatic phase shifts for the rho motion and from them the transfer probability. The rho motion corresponds approximately to that of the heavy particles and the theta to that of the light one. Semiclassical limiting expressions are obtained and provide a description of light particle tunneling at low energies for heavy–light–heavy particle systems. Numerical results are given and the present approximation is good for the systems investigated.