  Recently it has been proposed that the positron, the anti-particle analog of
the electron, is capable of forming an anti-matter bond in a composite system
of two hydride anions and a positron [Angew. Chem. Int. Ed. 57, 8859 (2018)].
In order to dig into the nature of this novel bond the newly developed
multi-component quantum theory of atoms in molecules is applied to this
positronic system. The topological analysis reveals that this species is
composed of two atoms in molecules, each containing a proton and half of the
electronic and the positronic populations. Further analysis elucidates that the
electron exchange phenomenon is virtually non-existent between the two atoms
and no electronic covalent bond is conceivable in between. On the other hand,
it is demonstrated that the positron density enclosed in each atom is capable
of stabilizing interactions with the electron density of the neighboring atom.
This electrostatic interaction suffices to make the whole system bonded against
all dissociation channels. Thus, the positron indeed acts like an anti-matter
glue between the two atoms.
