paper

Exploring the Statically Screened Correction to the Self-Energy: Charged Excitations and Total Energies of Finite Systems

arXiv:2110.04105 · doi:10.1103/PhysRevB.105.125121

Abstract

Electron correlation in finite and extended systems is often described in an effective single-particle framework within the approximation. Here, we use the statically screened second-order exchange contribution to the self-energy () to calculate a perturbative correction to the self-energy. We use this correction to calculate total correlation energies of atoms, relative energies, as well as charged excitations of a wide range of molecular systems. We show that the second-order correction improves correlation energies with respect to the RPA and also improves relative energies for many, but not all considered systems. While the full contribution does not give consistent improvements over , taking the average of and generally gives excellent results. Improvements over quasiparticle self-consistent , which we show to give very accurate charged excitations in small and medium molecules by itself, are only minor. quasiparticle energies evaluated with eigenvalue and orbitals from range-separated hybrids, however, are tremendously improved upon: The second-order corrected outperforms all existing methods for the systems considered herein and also does not come with substantially increased computational cost compared to for systems with up to 100 atoms.

Revised version as accepted by Physical review B (Phys. Rev. B 2022, 105, 125121, 10.1103/PhysRevB.105.125121) Compared to our first submission, a programming mistake in our first implementation has been corrected leading to different (better) results

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