CONFIGURATION INTERACTION IN TWO- AND THREE-ELECTRON ATOMS.

The ground states of the first four members of the helium isoelectronic series and the 22S and 22P states of lithium are calculated using a configuration‐interaction expansion in a complete denumerable set of single‐particle functions, with one adjustable scale parameter. The best energies for the two‐electron systems, obtained with 120‐term expansions, are E(H−) = −0.52748, E(He) = −2.90335, E(Li+) = −7.27945, and E(Be+ +) = −13.65504, in units of e2/a0. The energies for all but He are lower than any heretofore obtained with a configuration‐interaction approach. The dependence of energy on scale factor is found to be very pronounced, in contrast to the corresponding behavior for wavefunctions which contain the interparticle coordinates explicitly. The best energies for the lithium states, obtained with 208‐term expansions, are E(22S) = −7.47369 and E(22P) = −7.40366. The 22S energy is not as good as has been obtained with either expansions in terms of interparticle coordinates or configuration interactio...

[1]  C. Schwartz.  FINE STRUCTURE OF HELIUM , 1964 .

[2]  E. Davidson.  Natural Expansions of Exact Wavefunctions. III. The Helium-Atom Ground State , 1963 .

[3]  E. Burke.  Variational Calculation of the Ground State of the Lithium Atom , 1963 .

[4]  H. Schwartz.  FURTHER RESULTS CONCERNING HALF-INTEGRAL HYLLERAAS EXPANSIONS , 1963 .

[5]  C. Schwartz.  GROUND STATE OF THE HELIUM ATOM , 1962 .

[6]  M. Rotenberg.  Application of sturmian functions to the Schroedinger three-body problem: Elastic e+-H scattering , 1962 .

[7]  Frederick Albert Matsen IV,et al.  Perturbation Energy Coefficients and Ionization Potentials of the Ground State of Three- to Ten-Electron Isoelectronic Atomic Series , 1962 .

[8]  C. Pekeris,et al.  FINE STRUCTURE OF THE 2 $sup 3$P AND 3 $sup 3$P STATES OF HELIUM , 1962 .

[9]  A. Weiss.  Configuration Interaction in Simple Atomic Systems , 1961 .

[10]  C. Pekeris,et al.  1 1 S and 2 3 S States of Helium , 1959 .

[11]  P. Löwdin,et al.  Superposition of Configurations and Natural Spin Orbitals. Applications to the He Problem , 1959 .

[12]  R. E. Watson,et al.  APPROXIMATE WAVE FUNCTIONS FOR THE GROUND STATE OF HELIUM , 1958 .

[13]  L. H. Thomas,et al.  Numerical Calculation of the Wave Functions and Energies of the1S1and2S3States of Helium , 1958 .

[14]  M. E. Rose,et al.  Elementary Theory of Angular Momentum , 1957 .

[15]  Toichiro Kinoshita,et al.  GROUND STATE OF THE HELIUM ATOM , 1957 .

[16]  H. James,et al.  On the Ground State of Lithium , 1936 .

[17]  G. Breit.  Separation of Angles in the Two-Electron Problem , 1930 .

[18]  E. Hylleraas,et al.  Neue Berechnung der Energie des Heliums im Grundzustande, sowie des tiefsten Terms von Ortho-Helium , 1929 .

[19]  J. Bearden,et al.  Atomic energy levels , 1965 .

[20]  William F. Meggers,et al.  Quantum Theory of Atomic Structure , 1960 .