Excited $\Sigma$ states of the hydrogen-antihydrogen molecule

TL;DR

This paper calculates potential energy curves for excited states of the hydrogen-antihydrogen molecule using advanced basis functions, revealing their role in collision processes.

Contribution

It introduces detailed calculations of excited $ m ext{H}-ar{ ext{H}}$ states with explicit correlation, including free positronium, for the first time.

Findings

Excited leptonic states support ro-vibrational states near dissociation threshold.

These states are relevant for theoretical models of H-$ar{ ext{H}}$ collisions.

Potential curves for various symmetries were computed.

Abstract

Adopting explicitly correlated Kolos-Wolniewicz-type basis functions, the Born-Oppenheimer potential curves of a number of excited $\Sigma$ states of the hydrogen-antihydrogen system ($\bar{\rm H}$) were calculated for both, even and odd, Q symmetries, including also free positronium states. It is demonstrated that the excited leptonic states support ro-vibrational states with energies close to the ground-state dissociation threshold. As a consequence, the excited leptonic states need to be considered in theoretical treatments of ground-state H-$\bar{\mathrm{H}}$ collisions.