Nuclear dynamics in a positron-CO collision using close-coupling methods

Abstract

Apart from the electronic motion of the target in the molecular collision process, collision probabilities strongly depend on the dynamics of nuclear motions (rotation and vibration). Here we have studied this nuclear dynamical dependency of collision cross sections for a positron--carbon monoxide collision using rovibrational close-coupling, rotational laboratory frame close-coupling (rotational LFCC), and LFCC adiabatic nuclear vibration (LFCC-ANV) methods. Here we have computed the angle-integrated elastic and state-to-state rotational excitation, the elastic and state-to-state vibrational (summed over rotational) excitation, and the total (summed over rotational and vibrational) cross sections for the incident positron energy between 0.0 and 7.0 eV using the rovibrational close-coupling method. The rotational LFCC method is also employed to calculate elastic, (state-to-state) rotational excitation, and total cross sections. To estimate the effects of the nuclear dynamics we have calculated vibrational elastic and state-to-state vibrational excitation cross sections using the LFCC-ANV method. In these calculations the model correlation-polarization potential is used to include the correlation-polarization potential. The effect of nuclear dynamics on the collision probabilities is discussed comparing calculated total cross sections using the rovibrational close-coupling and the rotational LFCC method with other theoretical calculations and experimental results. The discussion includes comparison of the present vibrational $0\ensuremath{\rightarrow}1$ excitation process with the theoretical and measured values. The other vibrational and rotational elastic and excitation cross sections are also compared with the existing theoretical results and we have discussed the relevance of the effect of nuclear rotational and vibrational dynamics. We have also presented a comparison among the energy transfer parameters using different coupling schemes and have discussed the implications of the results.