Nature of the excited states of He_2
Abstract
The low-lying excited states of He_2 have been examined using spatially projected generalized-valence-bond wave functions. Typically the excited-state potential curves are repulsive at large R (internuclear distance) but exhibit an attractive well at small R. We find that the repulsion at large R results from an unfavorable exchange interaction of a Rydberg orbital mostly on one He with the two core orbitals on the other He. This arises from the restrictions on the molecular wave function implicit in the Pauli principle and is similar in nature to the repulsive pair-pair interactions between ground state He atoms. For R < 3a_0 the Rydberg orbital is large compared with R and the shape of the potential curve is determined by core-core interactions. For the A^1Σ_u^+ state, the calculated maximum in the potential curve is 0.0607 eV at 3.09 Å, in excellent agreement with experimentally derived values. Results are presented for several other excited states.
Additional Information
© 1975 American Physical Society. Received 5 August 1974. Partially supported by Grants Nos. GP-15423 and GP-40783X from the National Science Foundation. Based on the Ph.D. thesis (California Institute of Technology, 1972) of S. L. Guberman. The authors wish to thank Dr. D. L. Huestis, Dr. Ra C. Ladner, Dr. T. H. Dunning, and Dr. R. J. Blint for many informative conversations and for the use of their computer programs and subroutines.Attached Files
Published - WAG-0075-Guberman-He2.pdf
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Additional details
- Eprint ID
- 88423
- Resolver ID
- CaltechAUTHORS:20180801-082451277
- GP-15423
- NSF
- GP-40783X
- NSF
- Created
-
2018-08-01Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Other Numbering System Name
- WAG
- Other Numbering System Identifier
- 0075