Ground-state correlation energy of beryllium dimer by the Bethe-Salpeter equation
Résumé
Since the ’30s the interatomic potential of the beryllium dimer Be _2 2 has been both an experimental and a theoretical challenge. Calculating the ground-state correlation energy of Be _2 2 along its dissociation path is a difficult problem for theory. We present ab initio many-body perturbation theory calculations of the Be _2 2 interatomic potential using the GW G W approximation and the Bethe-Salpeter equation (BSE). The ground-state correlation energy is calculated by the trace formula with checks against the adiabatic-connection fluctuation-dissipation theorem formula. We show that inclusion of GW G W corrections already improves the energy even at the level of the random-phase approximation. At the level of the BSE on top of the GW G W approximation, our calculation is in surprising agreement with the most accurate theories and with experiment. It even reproduces an experimentally observed flattening of the interatomic potential due to a delicate correlations balance from a competition between covalent and van der Waals bonding.
Domaines
| Origine | Fichiers éditeurs autorisés sur une archive ouverte |
|---|---|
| Licence |