Three-electron Atomic Systems Research Articles

Nuclear charge expansion of the Hartree-Fock function of the 1s2s3p4P0state of the lithium isoelectronic sequence

The first-order Hartree-Fock equations of the 1s2s3p 4P0 state of three-electron atomic systems have been solved exactly. These solutions are used to evaluate the Hartree-Fock energy up to third order with high accuracy. The third-order Hartree-Fock energies for Li to Ne7+ are compared with those derived from experiment and other theoretical calculations.

Triply excited states of three-electron atomic systems

A formalism is discussed whereby many-electron systems may be described by a great number of product functions of different configurations in a manageable way. Calculations are made to find triply excited energy levels of three-electron atomic systems, using products of hydrogenic functions with a $Z$ equal to that of the nucleus. Results for the lowest $^{2}P^{o}$ and $^{2}S^{e}$ levels in the Li isoelectronic sequence, $Z=1 \mathrm{to} 10$, are presented. The results of calculations for the energies of $^{2}D^{e}$ triply excited states in ${\mathrm{He}}^{\ensuremath{-}}$ are also reported. The calculated energies are compared with available experimental and other theoretical values. Finally, the lowest $^{2}S^{e}$ and two lowest $^{2}P^{o}$ energy levels in the isoelectronic sequence are fitted by a $\frac{1}{Z}$ perturbation expansion. It is seen that this expansion can be used to estimate the energy levels of such states for higher nuclear charges.

Electronic correlation studies. III. Self-correlated field method. Application to2S ground state and2P excited state of three-electron atomic systems

The self-correlated field method is based on the insertion in the group product wave function of pair functions built upon a set of correlated ''local'' functions and of ''nonlocal'' functions. This work is an application to three- electron systems. The effects of the outer electron on the inner pair are studied. The total electronic energy and some intermediary results such as pair energies, Coulomb and exchange ''correlated'' integrals, are given. The results are always better than those given by conventional SCF computations and reach the same level of accuracy as those given by more laborious methods used in correlation studies. (auth)

Radio-Frequency Spectrum ofHe−3andHe−4

All independent energy intervals have been measured in the metastable $1s2s2p^{4}P$ state of the helium negative ions $^{4}\mathrm{He}^{\ensuremath{-}}$ and $^{3}\mathrm{He}^{\ensuremath{-}}$. These results are of sufficient precision to provide a critical test of any proposed wave functions for this state and, when adequate wave functions become available, can be used to test relativistic and radiative corrections in three-electron atomic systems.

Variational Calculations for Quartet States of Three-Electron Atomic Systems

Variational Calculations for Quartet States of Three-Electron Atomic Systems

Open shell calculations for the two- and three-electron ions

Open shell calculations are made for all the three-electron atomic systems of the second period of the periodic table. These results are compared with corresponding two-electron and experimental energies. It is noted that the improvement of open shell over closed shell calculations becomes less with increasing atomic number. In parallel trend the disparity of both from the experimental results increases with Z. An electron affinity of zero is found for the helium atom.