Bond breaking and bond formation: how electron correlation is captured in many-body perturbation theory and density-functional theory
Physical Review Letters 110, 146403 (2013)
Bond breaking and bond formation: how electron correlation is captured in many-body perturbation theory and density-functional theory
For the paradigmatic case of H2-dissociation we compare state-of-the-art many-body perturba- tion theory (MBPT) in the GW approximation and density-functional theory (DFT) in the exact- exchange plus random-phase approximation for the correlation energy (EX+cRPA). For an unbiased comparison and to prevent spurious starting point effects both approaches are iterated to full self- consistency (i.e. sc-RPA and sc-GW). The exchange-correlation diagrams in both approaches are topologically identical, but in sc-RPA they are evaluated with non-interacting and in sc-GW with interacting Green functions. This has a profound consequence for the dissociation region, where sc- RPA is superior to sc-GW . We argue that for a given diagrammatic expansion, the DFT framework outperforms the many-body framework when it comes to bond-breaking. We attribute this to the difference in the correlation energy rather than the treatment of the kinetic energy.
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- http://dx.doi.org/10.1103/PhysRevLett.110.146403
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- http://arxiv.org/abs/1210.8300