On the Nature of the Positronic Bond

Abstract

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 consists of two hydride anions and a positron [Angew. Chem. Int. Ed. 57, 8859–8864 (2018)]. In order to dig into the nature of this novel bond the newly developed multi‐component quantum theory of atoms in molecules (MC‐QTAIM) 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.

Covalent bonds in positron dihalides

“…In contrast, the positron densities ( ρ e + ) prominently accumulate in the internuclear region of e + [F – F – ] and e + [F – Cl – ], pointing out the formation of positron covalent bonds. 17 , 33 The remaining positronic systems also display accumulation of positron densities at the internuclear region along with insignificant change in the electron densities, consistent with the formation of positron bonds (see Fig. S2 † ).…”

“…The differences between molecular and atomic PBEs (DPBE/kJ mol À1 ) and EBEs (DEBE/kJ mol À1 ), as well as the dissociation energies (DE/kJ mol À1 ), are also given for the e + [F À Cl À ], pointing out the formation of positron covalent bonds. 17,33 The remaining positronic systems also display accumulation of positron densities at the internuclear region along with insignicant change in the electron densities, consistent with the formation of positron bonds (see Fig. S2 †).…”

“…APMO and other multicomponent approaches have been regularly applied to study positron-containing atoms and molecules. 18,[21][22][23][24][25][26][27][28][29][30][31][32][33][34] A summary of APMO expressions can be found elsewhere. 20 In this paper, we label the multicomponent methods aer the purely electronic ones, e.g., APMO/HF for Hartree-Fock, APMO/CI for conguration interaction, APMO/ MP2 for second-order Møller-Plesset perturbation theory, etc.…”

Two positrons can form a chemical bond in (PsH)2

“…The two (chopped) peaks of the electronic distribution are clearly visible in Figure 3. The positron distribution surrounding the two Hions acts as a positronic glue 26,27 keeping the system together.…”

Taxas de aniquilação em moléculas positrônicas

“…Por fim, deve-se mencionar que recentemente surgiram evidências da existência de outro tipo de molécula positrônica. Cálculos numéricos mostram que o sistema formados por um pósitron e doisânions de hidrogênio e + H − H −é eletronicamente estável [61,62], assim como os sistemas formados por e + X − Y − , com X, Y = F, Br, Cl [63]. Nesses casos, a densidade do pósitron está acumulada na região entre os dois núcleos, evidenciando que há uma espécie de ligação covalente positrônica que mantém osânions unidos.…”