Metastable He sub 2 sup minus and its autodetachment spectra: An accurate coupled-cluster study

Journal Article · Fri Sep 01 00:00:00 EDT 1989 · Physical Review (Section) A: General Physics; (USA)

DOI:https://doi.org/10.1103/PhysRevA.40.2253· OSTI ID:5397340

Pluta, T; Bartlett, R J ^[1]; Adamowicz, L ^[2]

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1. Quantum Theory Project, Department of Chemistry and Department of Physics, University of Florida, Gainesville, Florida 32611 (US)
2. Department of Chemistry, University of Arizona, Tucson, Arizona 85721

The unusual autodetachment spectrum of metastable He{sub 2}{sup {minus}} is studied theoretically, using high-level coupled-cluster methods and hybrid numerical and Slater orbital basis sets. By obtaining accurate curves for the repulsive wall of the ground He{sub 2}({ital X} {sup 1}{Sigma}{sub {ital g}}{sup +}) state, the excited He{sub 2}({ital a} {sup 3}{Sigma}{sub u}{sup +}) state, and the metastable He{sub 2}{sup {minus}}({sup 4}{Pi}{sub g}) state, we are able to provide an alternative explanation for the experimental observations, which had cast doubt on the veracity of the accepted curve for the repulsive part of the He{sub 2}({ital X}{sup 1}{Sigma}{sub g}{sup +}) potential. We attribute the experimental peak at 15.78{plus minus}0.13 eV to transitions of vibrationally excited states ({nu}=2 and higher) of He{sub 2}{sup {minus}} to the He{sub 2}(X {sup 1}{Sigma}{sub {ital g}}{sup +}) continuum, since the {ital v}=0 transition would have a value 1 eV less. An error of this size is considered to be far outside the error bars for highly accurate correlated {ital ab} {ital initio} calculations. The electron affinity of the {sup 4}{Pi}{sub g} state of the anion (measured relative to {ital a} {sup 3}{Sigma}{sub u}{sup +}) is computed to be 0.201 and 0.212 eV for different basis sets, compared to an experimental value of 0.175{plus minus}0.032 eV.

• OSTI ID: 5397340
• Journal Information: Physical Review (Section) A: General Physics; (USA), Journal Name: Physical Review (Section) A: General Physics; (USA) Vol. 40:5; ISSN PLRAA; ISSN 0556-2791
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
AFFINITY
ANIONS
AUTOIONIZATION
CALCULATION METHODS
CHARGED PARTICLES
DIAGRAMS
DIMERS
ELEMENTS
ENERGY
ENERGY-LEVEL TRANSITIONS
FLUIDS
GASES
HELIUM
IONIZATION
IONS
MOLECULAR IONS
NONMETALS
POTENTIAL ENERGY
RARE GASES