Theoretical investigations of positron affinities and their structure-dependent properties of carbon dioxide clusters (CO2)n (n = 1–5)

Abstract

Although positron binding to van der Waals intermolecularly bonded clusters of non-polar carbon dioxide (CO₂) molecules was experimentally suggested, the positron binding feature has been poorly understood. We investigated positron affinities (PAs) by means of multi-component configuration interaction calculations for various structures of (CO₂)_n (n = 1–5) obtained by the single-component artificial force induced reaction (SC-AFIR) method. Our calculations showed that CO₂ monomers do not bind a positron, whereas positron affinities for clusters tend to increase with an increase in the cluster size. Our regression analyses for determining PAs with electrostatic and structural properties of conformations revealed a significant conformer effect due to which structural characteristics such as flatness may have a strong influence on PA for loosely bound positronic complexes of (CO₂)_n.