Probing the molecular structure and properties of neutral and anionic ground states of SO2 and CO2

摘要

In this present investigation, the structures of SO2, SO2-, CO2 and CO2- as well as the adiabatic electron affinities of the corresponding SO2 and CO2 neutral parents are computed using the infinite-order coupled-cluster method with all singles and doubles and non-iterative inclusion of triple excitations (CCSD(T)) and the Moller-Plesset perturbation theory up to the second order (MP2). The molecular structure, fundamental frequencies with their corresponding intensities and electron localization functions of SO2 and SO2- are interpreted from respective ground-state optimized electronic structures calculated and compared with other simple tri-atomic molecules CO2 and CO2-, respectively. The electron localization function are then quantified and the second-order perturbation energies for different oxygen lone pairs (n) to sigma* and pi* interactions of S-O and C-O bond orbitals have been calculated by carrying out NBO analysis and the results are compared. The change in the electronic structure of the molecule after the attachment of a low-energy (<= 15 eV) electron, thus forming a transient negative ion (TNI), can be interpreted from the n -> sigma* and n -> pi* interactions. The potential energy curves of SO2-SO2- and CO2- CO2- pairs are calculated as a function of S-O and C-O bond distance and bending angle. The adiabatic electron affinity of SO2 is calculated to be positive while that of CO2 is negative.