Classical trajectory and adiabatic channel study of the transition from adiabatic to sudden capture dynamics .3. Dipole-dipole capture

Classical trajectory (CT) calculations of dipole-dipole capture processes are performed over wide ranges of conditions. Besides the anisotropic dipole-dipole potential, an isotropic dispersion potential is accounted for. The Massey parameter of the system characterizes the transition between adiabatic and nonadiabatic (sudden) dynamics. In the adiabatic limit, under classical conditions, CT and statistical adiabatic channel model (SACM) give identical thermal capture rate constants which can be expressed in simple parametrized form The transition from quantum to classical SACM rate constants is represented analytically as well. Furthermore, harmonic oscillator versions of SACM for dipole-dipole capture are compared with the corresponding models for ion-dipole and ion-quadrupole capture. (C) 1996 American Institute of Physics.