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 (ρ,ϑ) 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 ρ. They provide an effective potential for the ρ motion and are used to obtain the elastic adiabatic phase shifts for the ρ motion and from them the transfer probability. The ρ motion corresponds approximately to that of the heavy particles and the ϑ 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.