Relativistic effect on total energies for determination of correlation energies of atoms from their experimental total energies

Journal Article · Sun Oct 15 04:00:00 EDT 1989 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.456763· OSTI ID:5474566

Anno, T ^[1]; Teruya, H ^[2]

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1. Laboratory of Chemistry, College of General Education, Kyushu University, Ropponmatsu, Fukuoka, 810 Japan (JP)
2. Kumamoto University, College of Medical Science, Kuhonji, Kumamoto, 862 Japan

Relativistic effect {ital E}{sup rel} upon the total electronic energy of an atom is discussed with particular reference to obtaining the nonrelativistic total energy {ital E}{sup exact} from the experimental total energy. Numerical values of this effect obtained by various authors by different nonempirical methods are compared for neutral atoms of rare-gas elements. It is shown that methods either of a Hartree--Fock-type or of a Dirac--Hartree--Fock-type give much the same {ital E}{sup rel} value for He through Ar. It is pointed out that {ital E}{sup rel} calculated with Hartree--Fock wave functions is not adequate for use in obtaining {ital E}{sup exact} from the experimental total energy and that the {ital E}{sup rel} value calculated with wave functions including electron correlation should work well, although an actual demonstration can be done only for two-electron systems for lack of data. A semiempirical formula is therefore proposed, which is useful for least-squares fit of experimental total energies of isoelectronic series of atoms to extract nonrelativistic total energies along with the relativistic effect. From nonrelativistic energies thus derived, semiempirical values of correlation energies of atoms are obtained. The results thus obtained are in reasonable agreement with correlation energies derived by Clementi along somewhat different lines. The power series expansion in {ital Z} of the fitted formula for the He series shows that numerical values of expansion coefficients agree reasonably well with the corresponding values obtained by accurate relativistic and nonrelativistic {ital Z} expansion-type calculations.

• OSTI ID: 5474566
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 91:8; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ATOMS
CORRECTIONS
CORRELATIONS
ELECTRON CORRELATION
ELECTRONIC STRUCTURE
ELEMENTS
FIELD THEORIES
FLUIDS
GASES
GENERAL RELATIVITY THEORY
HARTREE-FOCK METHOD
NONMETALS
POWER SERIES
RADIATIVE CORRECTIONS
RARE GASES
RELATIVITY THEORY
SERIES EXPANSION