Joseph B. Mann

Hartree-Fock Compton profiles for the elements

Orbital and total-atom Compton profiles are given for the elements. Hartree-Fock wavefunctions were used in the numerical calculations for atomic numbers 1 less than or equal to Z less than or equal to 36 and relativistic Dirac- -Hartree--Fock wavefunctions for atomic numbers 36 less than or equal to Z less than or equal to 102.

Compton Scattering Factors for Spherically Symmetric Free Atoms

Incoherent scattering factors for all spherically symmetric free atoms have been computed from numerical SCF Hartree—Fock wavefunctions. The complete Waller—Hartree theory with all exchange terms has been used.

Ionization Cross Sections of the Elements Calculated from Mean‐Square Radii of Atomic Orbitals

Relative ionization cross sections for single ionization by electron impact on free gaseous atoms have been calculated by utilizing a summation of the mean‐square orbital radii of outer electrons. A previous calculation of the cross sections by Otvos and Stevenson was in only fair agreement with experimental data due to the use of incorrect mean‐square radii, and to the method of summation of electron‐shell contributions to the total cross sections. Hartree—Fock calculations of orbital wavefunctions have been carried out for all of the elements. Mean‐square radii of atomic orbitals from the Hartree—Fock calculations were corrected approximately for relativistic effects. The ionization cross sections obtained from the summations were normalized at argon and compared with experimental values. The computed maximum cross sections are a considerable improvement over past theoretical values.

Thermal Conductivity of Helium and Hydrogen at High Temperatures

A steady‐state hot wire method for measuring the thermal conductivity of light gases in the temperature range 1200° to 2100°K is described. In contrast to other methods, free convection currents and large temperature gradients occur; convection effects are shown to be negligible, and the experimental procedure for eliminating the large gradient effects is described. The thermal conductivity of helium is found to follow the equation λ×106=991+0.678(T—1200) cal/sec cm deg over the temperature range covered. That for hydrogen is λ×106=1434+1.257(T—1200) cal/sec cm deg.

SCF Relativistic Hartree–Fock Calculations on the Superheavy Elements 118–131

The energies of a number of configurations of the elements with atomic numbers 118–131 were computed by means of the relativistic Hartree–Fock method to establish the probable ground states. The series of elements beginning at 121 differs markedly from the lanthanide and actinide series because spinp–orbit and direct relativistic effects cause the 8p1/2 electron states to be partially filled before the 7d3/2 states. The inner shell of 5g electrons begins to fill at element 125. The Breit magnetic interaction energy is calculated by a perturbation method; an approximate correlation energy correction is included. Isotopic mass effects on the atom total energy and on the electron eigenvalues are discussed.

Excitation collision strengths for iron ions calculated with a distorted wave method

Collision strengths have been calculated for electron impact excitation of many iron ions, using a distorted wave method. The ions studied were Fe X, and Fe XV to Fe XXVI. Tabulations are provided of (1) collision strength vs energy; (2) mixing coefficients needed to define the initial and final states; and (3) fit parameters for the collision strengths, to be applied in the calculation of excitation rate coefficients.

Self-consistent relativistic Dirac-Hartree-Fock calculations of lanthanide atoms

The results of relativistic Dirac-Hartree-Fock calculations of the electronic structure and energies of elements are presented for the ground configurations of the lanthanide atoms. Exchange termsare included without approximation in the calculation; corrections for Breit magnetic interactions, retardation, and correlation are included as perturbations. Tabulations are given for total atom energies, orbital binding energies, orbital radial expectation values 〈rn〉 (n from −3 to +6), Slater electrostatic interaction integrals Fk and Gk, total radial charge densities, and the parameters for determining electron charge densities within the nucleus. Some comparisons are made with results from other methods of calculation.

Collision strengths and oscillator strengths for excitation to the n = 3 and 4 levels of neon-like ions

Collision strengths are given for the 88 possible fine-structure transitions between the ground level and the n = 3 and 4 levels in 20 neon-like ions with nuclear charge number Z in the range 18 less than or equal toZless than or equal to74. The results are given for the nine impact-electron energies in threshold units X = 1.0, 1.2, 1.5, 1.9, 2.5, 4.0, 6.0, 10.0, and 15.0. In addition, electric dipole oscillator strengths obtained by various methods are given. copyright 1987 Academic Press, Inc.

Ionization of U, UO, and UO2 by Electron Impact

The first ionization potential of uranium and the first appearance potentials of UO and UO2 by electron impact have been measured in a mass spectrometer, using the retarding potential difference (RPD) method. Small modifications of the RPD source are described. Crucibles of zirconium diboride were found to be preferable to tantalum crucibles for vaporization of uranium metal. Correction is made to the uranium appearance potential for thermally excited low‐lying levels of the uranium atom, and for the several possible ionization paths. The ionization potential for uranium is 6.11±0.05 eV; for UO and UO2 the appearance potentials are 5.72±0.06 eV and 5.5±0.1 eV. Ionization probability curves were determined for U and UO.

SCF Hartree-Fock results for elements with two open shells and the elements francium to nobelium

Abstract Hartree-Fock calculations of the electronic structure and energies of the elements from hydrogen to lawrencium were made. Exchange terms were included without approximation. The calculations were done with the configuration average energy stationary to first order. Results are presented here for the ground state configurations of elements Cr, Cu, Nb, Mo, Ru, Rh, Pd, Ag, La, Ce, Gd, Pt, and Au (all but Pd have two open shells), and for the elements Z = 87 to Z = 102; also included are results for neon, argon, krypton, xenon, radon, and mercury. The results consist of total average energy; one-electron eigenvalues and I(nl) energies; two-electron interaction energy integrals Fk, Gk; radial expectation values, the radii of orbital principal maxima, the radial wavefunctions, and a constant suitable for obtaining wavefunctions at very small radii.