Variational calculations for /sup 4/He I: Improved energies for singlet and triplet n D and n F levels (n = 3--8)

Journal Article · Fri Apr 01 04:00:00 EST 1988 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.37.2259· OSTI ID:5292714

Sims, J S; Martin, W C

Hylleraas method variational calculations with up to 458 expansion terms are reported for the n /sup 1/D, n /sup 3/D terms and for the n /sup 1/F, n /sup 3/F terms (n = 4--8) of neutral helium. Convergence arguments are presented to obtain new estimates of the exact nonrelativistic energies of these terms. The reliability of the estimates ranges from 3 x 10/sup -10/ a.u. in the worst case to 10/sup -11/ a.u. in the best case. The nonrelativistic singlet and triplet energies are combined with previously calculated values for relativistic and other small energy contributions to evaluate the total ionization energies for the n D and n F levels. Comparisons of the n /sup 1/D and n /sup 3/D energies with other calculations and available data yield improved values for relativistic contributions. The calculated relativistic n F ionization energies agree with values based on core-polarization theoretical n G and n H energies within deviations of 3 MHz (5 x 10/sup -11/ a.u.) for n = 5 to 1 MHz (1.5 x 10/sup -11/ a.u.) for n = 7,8. The calculated n F fine-structure separations generally agree with experiment for n = 5--8 within uncertainties of the order of 1 to 0.1 MHz. Predicted values given for the 4 F fine-structure separations and the 4/sup 1/F ionization energy are probably accurate within a few MHz.

• Research Organization: National Bureau of Standards, Gaithersburg, Maryland 20899
• OSTI ID: 5292714
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 37:7; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
CONVERGENCE
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY LEVELS
FLUIDS
FUNCTIONS
GASES
HELIUM
MULTIPLETS
NONMETALS
RARE GASES
SERIES EXPANSION
TRIPLETS
VARIATIONAL METHODS
WAVE FUNCTIONS