On the nature of the two-positron bond: Evidence for a novel bond type

TL;DR

This paper investigates a novel two-positron bond in (PsH)2, revealing it as a new type of electrostatic interaction distinct from traditional covalent or electronic bonds, supported by advanced quantum calculations.

Contribution

The study introduces and characterizes a new two-positron bond mechanism, termed gluonic, using multi-component quantum theories and ab initio methods, expanding the understanding of exotic bonding.

Findings

The two-positron bond is primarily stabilized by electrostatic interactions.

Positron exchange is marginal in this bond, unlike in electron-based bonds.

The bond is a new, non-covalent, electrostatic interaction, termed gluonic.

Abstract

The nature of the newly proposed two-positron bond in (PsH)2, which is composed of two protons, four electrons and two positrons, is considered in this contribution. The study is done at the multi-component-Hartree-Fock (MC-HF) and the Diffusion Monte Carlo (DMC) levels of theory by comparing ab initio data, analyzing the spatial structure of the DMC wavefunction, and applying the multi-component quantum theory of atoms in molecules and the two-component interacting quantum atoms energy partitioning schemes to the MC-HF wavefunction. The analysis demonstrates that (PsH)2 to a good approximation may be conceived of two slightly perturbed PsH atoms, bonded through a two-positron bond. In contrast to the usual two-electron bonds, the positron exchange phenomenon is quite marginal in the considered two-positron bond. The dominant stabilizing mechanism of bonding is a novel type of classical electrostatic interaction between the positrons, which are mainly localized between nuclei, and the surrounding electrons. To emphasize its uniqueness, this mechanism of bonding is proposed to be called gluonic which has also been previously identified as the main deriving mechanism behind formation of the one-positron bond in [H-, e+, H-]. We conclude that the studied two-positron bond should not be classified as a covalent bond and it must be seen as a brand-new type of bond, foreign to the electronic bonding modes discovered so far in the purely electronic systems.