EFFECTS OF NON-ADLABATIC TRANSITION ON NUCLEAR DYNAMICAL PROCESSES

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(1) Analytical formulae for the S-matrix are derived for a two-state curve crossing problem in the presence of potential barriers by using a three turning point semiclassical theory and a matrix formalism for the non-adiabatic transition. They satisfy the unitarity condition and the elasitc and inelasitc S-matrix elements reduce to improved Landau-Zener-Stuckelberg formulae at high energies where the existence of the potential barrier can be ignored. We discuss qualitative behaviors of the semiclassical S-matrix elements in the weak and strong coupling limits, i.e. in the limits where the one-way Landau-Zener transition probability p* 1 and p * 0, respectively. We also discuss the possible interplay between the Landau Zener transtion and the potential resonance. In such a system as ^<13>C + ^<17>O, we show that the inelastic partial cross section attributed to the Landau-Zener transition is strongly enhanced by the potential resonance in case that the avoided crossing exists inside the … More Coulomb barrier. We also show the inelastic partial cross section is strongly suppressed by the destructive interference between the phase accompanied with the Landau-Zener transition and the phase-shifts for the adiabatic potential scattering when the avoided crossing exists outside the Coulomb barrier.(2) The roles of higher order coupling of sufface vibrations and anharmonicites, the possibilities of extracting the sign of the deformation, effects of adiabatic quantum tunneling and of finite width of excited states are investigated by the theoretical aanlyses of the several kinds of experimental data in heavy-ion fusion reactions at near and below the Coulomb barrier. We predicted such a new mechanism as grory in the shadow of rainbow in heavy-ion scattering. It is also shown that the bombarding energy-dependence of the cross section at very small angle is effective to identify it.(3) Shielding effect of the electrons bounded in the target nuclei on nuclear fusion reactions at very low energies is now investigated. The numerical calculation is now in progress in the case of d + D system by using the dynamical norm method and non-adiabatic potential method equivalent to that.(4) The collision between a cluster and a highly charged ion, and subsequent production of the highly charged cluster, are investigated in the time-dependent local-density approximation. The multiple electron transfer passing over the saddle of the potential barrier is predicted and is in good agreement with an estimate by the simple classical overbarrier model. A microscopic calculation of the collision between highly charged ion and rare gas atom in the same approximation has been carried out. The calculated charge transfer cross sections are in fair agreement with measurements, the semi-classical formula and the molecular classical overbarrer model. Less