2015/10/26 by Yang Yang, Kieron Burke, Weitao Yang · 1 citation
Physics and Astronomy · #Advanced Chemical Physics Studies #Cold Atom Physics and Bose-Einstein Condensates #Density functional theory #Excitation #Nuclear physics research studies #Phase (matter) #Quantum #Quantum defect #Random phase approximation #Rydberg atom #Rydberg formula #Series (stratigraphy) #physics.chem-ph
paper · pdf · doi:10.1080/00268976.2015.1123316
arxiv created 2015/10/26 · openalex publication_date 2015/12/21 · arxiv updated 2016/05/04 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
The accuracy of calculations of atomic Rydberg excitations cannot be judged by the usual measures, such as mean unsigned errors of many transitions. We show how to use quantum defect (QD) theory to (a) separate errors due to approximate ionisation potentials, (b) extract smooth QDs to compare with experiment, and (c) quantify those defects with a few characteristic parameters. The particle–particle random phase approximation (pp-RPA) produces excellent Rydberg transitions that are an order of magnitude more accurate than those of time-dependent density functional theory with standard approximations. We even extract reasonably accurate defects from the lithium Rydberg series, despite the reference being open-shell. Our methodology can be applied to any Rydberg series of excitations with four transitions or more to extract the underlying threshold energy and characteristic QD parameters. Our pp-RPA results set a demanding challenge for other excitation methods to match.