2020/09/30 by Carlos Mejuto-Zaera, Guorong Weng, Mariya Romanova +4
Physics and Astronomy · #Advanced Chemical Physics Studies #Cold Atom Physics and Bose-Einstein Condensates #Perturbation (astronomy) #Perturbation theory (quantum mechanics) #Quasiparticle #Spectral line #Spectroscopy and Quantum Chemical Studies #Valence (chemistry) #Vertex (graph theory) #physics.chem-ph
paper · pdf · doi:10.1063/5.0044060
published as J. Chem. Phys. 154, 121101 (2021) · 14 pages, 3 figures, plus SI
openalex created_date 2020/09/11 · arxiv created 2020/12/01 · openalex publication_date 2021/03/22 · arxiv updated 2021/03/23 · openalex updated_date 2026/08/06
Photo-emission spectroscopy directly probes individual electronic states, ranging from single excitations to high-energy satellites, which simultaneously represent multiple quasiparticles (QPs) and encode information about electronic correlation. The first-principles description of the spectra requires an efficient and accurate treatment of all many-body effects. This is especially challenging for inner valence excitations where the single QP picture breaks down. Here, we provide the full valence spectra of small closed-shell molecules, exploring the independent and interacting quasiparticle regimes, computed with the fully correlated adaptive sampling configuration interaction method. We critically compare these results to calculations with the many-body perturbation theory, based on the GW and vertex corrected GWΓ approaches. The latter explicitly accounts for two-QP quantum interactions, which have often been neglected. We demonstrate that for molecular systems, the vertex correction universally improves the theoretical spectra, and it is crucial for the accurate prediction of QPs as well as capturing the rich satellite structures of high-energy excitations. GWΓ offers a unified description across all relevant energy scales. Our results suggest that the multi-QP regime corresponds to dynamical correlations, which can be described via perturbation theory.