Multiconfiguration Hartree-Fock calculations of low-lying excited {sup 2}{ital S} states in lithium

Journal Article · Wed Nov 01 04:00:00 EST 1995 · Physical Review A

DOI:https://doi.org/10.1103/PhysRevA.52.4262· OSTI ID:132915

Joensson, P; Froese Fischer, C ^[1]; Bieron, J ^[2]

---

1. Department of Computer Science, Vanderbilt University, Box 1679 B, Nashville, Tennessee 37235 (United States)
2. Atomic Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

The hyperfine interaction constants, specific-mass-shift parameters, and total energies for the 3{ital s} {sup 2}{ital S} and 4{ital s} {sup 2}{ital S} states in lithium were calculated using the multiconfiguration Hartree-Fock method. The configuration expansions were obtained with the active space method, where configuration state functions are generated by excitations from the reference configuration to an active set of orbitals. The active set was increased in a systematic way, allowing the convergence of the studied parameters to be monitored. The obtained nonrelativistic energies are close to the lowest-upper-bound estimates from Hylleraas calculations. Whereas the convergence rate of the hyperfine interaction constants with respect to the increasing basis in the Hylleraas calculations degrades appreciably for higher states in the Rydberg series, no such effect could be seen for the multiconfiguration Hartree-Fock calculations. The uncertainties of the calculated hyperfine interaction constants are estimated to be less than three parts in a thousand for both of the studied states. The value for the 3{ital s} {sup 2}{ital S} state is in excellent agreement with results from relativistic many-body perturbation theory calculations, but is well outside the error bars from a recent precision measurement using Stark spectroscopy.

• Sponsoring Organization: USDOE
• OSTI ID: 132915
• Journal Information: Physical Review A, Journal Name: Physical Review A Journal Issue: 5 Vol. 52; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ELECTRONIC STRUCTURE
ERRORS
GHZ RANGE 01-100
GHZ RANGE 100-1000
HARTREE-FOCK METHOD
HYPERFINE STRUCTURE
LITHIUM
MANY-BODY PROBLEM
S STATES