e+(PsH)2: A three-positron molecule with a positronic chemical bond

Abstract

Two new positronic molecules have been recently discovered: [Angew. Chem. Int. Ed. 57, 8859-8864 (2018)] and (PsH)2 [J. Chem. Phys. 155, 054306 (2021)]. These molecules seem to be stabilized by a new type of bond, the positronic bond, where one or two positrons are directly responsible for the bonding of two otherwise repelling negative ions. We show that a positron can attach to (PsH)2 to form a locally stable species with three positrons whose potential energy curve shows an equilibrium structure at about 8 bohr and a binding energy of 11.5(5) mhartree with respect to the dissociation into PsH + e+PsH. This molecule, tentatively called e+(PsH)2, is the first system with three positrons discovered.

The three-center two-positron bond

“…A similar situation was found for positron bonded dihydrides. Previous studies pointed out that (I) e + [H 2 2− ], 7–9 (II) 2e + [H 2 2− ], 10 and (III) 3e + [H 2 2− ] 11 are thermodynamically unstable with respect to dissociation into (I′) H 2 + Ps − , (II′) H 2 + Ps 2 and (III′) H 2 + Ps 2 + e + , respectively. The local range of stability for the systems I, II and III was explored by comparing the potential energy curves (PECs) for the (I, I′), (II, II′) and (III, III′) pairs.…”

“…Theoretical studies have evidenced the formation of locally stable systems composed of two repelling atomic anions and one-tothree positrons. The anti-particles are mainly responsible for the conformers' stabilization, thus expanding the definition of chemical bonding beyond the ordinary purely electronic systems 4,[6][7][8][9][10][11] . In this work, we have found that two positrons can form a locally stable bound state with three hydride anions in a D 3h configuration and singlet spin state.…”

“…Bressanini has conjectured that a system analogous to H 3 + with three protons, six electrons, and two positrons, could be stable. 10,11 Based on high-level QMC simulations, we demonstrate that this conjectured system, denoted as 2e + [H 3…”

“…The present study further explores positronic bonding mechanisms beyond the previously studied two-center to three-center systems. Bressanini has conjectured that a system analogous to H + 3 with three protons, six electrons, and two positrons, could be stable 10,11 .…”

“…Bressanini has conjectured that a system analogous to H 3 + with three protons, six electrons, and two positrons, could be stable. 10,11…”