2006/01/31 by M. W. J. Bromley, J. Mitroy · 2 citations
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Atomic and Molecular Physics #Inorganic Fluorides and Related Compounds #physics.atom-ph #physics.chem-ph #physics.comp-ph
paper · pdf · doi:10.1002/qua.21231
published as Int.J.Quantum Chemistry 107 (2007) 1150 · 11 pages, 7 figures, revtex format, submitted to Int.J.Quantum Chemistry
arxiv created 2006/07/26 · openalex publication_date 2006/10/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Abstract The configuration interaction (CI) method, using a very large Laguerre orbital basis, is applied to the calculation of the He ground state. The largest calculations included a minimum of 35 radial orbitals for each ℓ ranging from 0 to 12, resulting in basis sets in excess of 400 orbitals. The convergence of the energy and electron–electron δ‐function with respect to J (the maximum angular momenta of the orbitals included in the CI expansion) were investigated in detail. Extrapolations to the limit of infinite angular momentum using expansions of the type Δ X J = A X [ J + 1/2] − p + B X [ J + 1/2] − p −1 + …, gave an energy accurate to 10 −7 Hartree and a value of 〈δ〉 accurate to about 0.5%. Improved estimates of 〈 E 〉 and 〈δ〉, accurate to 10 −8 Hartree and 0.01%, respectively, were obtained when extrapolations to an infinite radial basis were done prior to the determination of the J → ∞ limit. Round‐off errors were the main impediment to achieving even higher precision, since determination of the radial and angular limits required the manipulation of very small energy and 〈δ〉 differences. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007