Many-body theory of positron interactions with molecules

The strong positron-molecule correlations are accounted for via a diagrammatic description of the self-energy of the positron in the field of the molecule.<br><br>It is constructed by solving the Bethe-Salpeter equations for the two-body propagators in the positron-electron, positron-hole, and electron-hole channels.

Positron binding to negative ions, atoms, and molecules in the fixed-nuclei approximation is studied. For positron binding to molecules, the approach [published in J. Hofierka, B. Cunningham, C. M. Rawlins, C. H. Patterson and D. G. Green, Nature 606, 688 (2022)]: (i) gives the first ab initio calculations in close agreement with data from over two decades of pioneering experiments; (ii) provides fundamental insight into the role of correlations including quantifying the role of virtual-positronium formation in enhancing binding in polar molecules and enabling binding in non-polars, and increasing annihilation rates by 2 to 3 orders of magnitude; and (iii) proposes a computationally less expensive approach to account for the important process of virtual-positronium formation, demonstrated by predicting binding energies in DNA nucleobases.