Calculation of Effective Potentials for the Study of Shape Resonances in Open Shell Diatomics

Abstract

Shape resonances play a dominant role in low energy electron-molecule dynamics. Among the numerous ones observed in photoionization, elastic or vibrationally inelastic electron scattering, a few cases are now well understood. It has been confirmed theoretically that they originate in a particular shape of the electron-target interaction potential as suspected from experiment. However, we are still far from understanding the systematics of experimental data, even in the simple case of the first row diatomics like N₂, CO, NO, O₂ ⁽¹⁾ At this stage, there is still room for a theoretical tool that would satisfy the following requirements:

• 1o/ to remain simple enough to be actually applied to a large number of cases without too heavy a computational effort.

• 2o/ to provide a simple physical picture of the process.

• 3o/ to be applicable to a wide class of molecules including closed and open shell ones, diatomics and polyatomics.

• 4o/ to be fully ‘ab initio1, without any adjustable parameter, so as to be used as a tool for the interpretation of experimental data.