Vibrational excitation in the e+CO2 system: Nonlocal model of Sigma Pi vibronic coupling through the continuum
Abstract
We present our model of the e+CO2 system that has been used to calculate the two-dimensional electron energy-loss spectrum of CO2 for incoming electron energies up to 5 eV reported in our Letter [Phys. Rev.
Lett. 129, 013401 (2022)]. We derive the effective Hamiltonian that describes the nonlocal dynamics of CO2- within the full vibrational space and in the presence of the (2)Sigma(+)(g) virtual state and the Renner-Teller coupled (2)Pi(u) shape resonance.
The electronic states are represented by three discrete states that interact directly with each other and also indirectly through the electronic continuum that consists of s and p partial waves. Based on our ab initio fixed-nuclei R-matrix calculations, parameters of the model are determined using a fitting procedure that utilizes the high symmetry of the system.
The topology of the resulting complex potential energy surfaces is discussed. The model is constructed in such a way that the Hamiltonian expressed in a harmonic vibrational basis of the neutral molecule is a sparse matrix which enabled us to solve the multidimensional dynamics of vibrational excitation using iterative methods based on Krylov subspaces.