J. T. Waber

Bio: J. T. Waber is an academic researcher from Northwestern University. The author has contributed to research in topics: Wave function & Dirac (software). The author has an hindex of 4, co-authored 4 publications receiving 1013 citations.

Orbital Radii of Atoms and Ions

Abstract: Radii corresponding to the principal maxima in the radial distribution functions r2ψi2(r) have been obtained for the ground states of all the atoms in the periodic table. The relativistic wavefunctions employed were solutions of the Dirac equations. Slater's ρ⅓ method for including exchange and Latter's method for the self‐interaction correction were used in ``creating'' the potential.The radii corresponding to these maxima are used as measures of the size of each orbital. The relation between the orbital radii of the valence electrons is shown as plots for the first, second, and third series of transition elements.In the elements below nobelium, only four maxima occur in the total charge‐density function. The relation of these maxima to the shell structure of the atom and the effect of shielding by outer electrons are discussed. The effect of the relativistic contraction on orbitals of low angular momentum is shown.

SCF Dirac–Slater Calculations of the Translawrencium Elements

Abstract: Total energies of several configurations of the elements in the range of atomic numbers 104–132 were computed using the Liberman–Waber–Cromer program to determine the probable ground‐state configurations. These calculations provide evidence for eka‐actinium (s2d) at 121, partial filling of the 6f shell through 124 and beginning of a new superactinide series at element 125, in which the 5g shells fill progressively as the atomic number increases.

Relativistic Calculation of Anomalous Scattering Factors for X Rays

Abstract: Anomalous scattering factors Δf′ and Δf″ have been calculated relativistically for Cr, Fe, Cu, Mo, and Ag Kα radiations for the atoms Li through Cf. An interpolation scheme for other wavelengths is included in a separate report. Relativistic calculations of the photoelectric cross section have been made and the integral for the principal contribution to Δf′ has been evaluated numerically without approximation to the form of the cross section‐vs‐energy curve, as has been done in previous calculations. Many of the results are significantly different from previous calculations. Where experimental values exist, agreement for Δf″ is improved. For the rare gases, except for xenon, agreement between Δf′ and experiment is improved. Because of the more rigorous evaluation of Δf′ from cross‐section information, it is presumed that the present Δf′ values are more accurate than previous calculated values. Calculated mass absorption coefficients for the elements are included as incidental information.

A technique for relativistic spin-polarised calculations

Abstract: A technique for reduction of the Dirac equation, which initially omits the spin-orbit interaction (thus keeping spin as a good quantum number), but retains all other relativistic kinematic effects such as mass-velocity, Darwin, and higher order terms is presented. The spin-orbit interaction can be included as a perturbation once the 'relativistic' spin-polarised bands and wavefunctions have been obtained. The technique is used together with the local spin density approximation for exchange and correlation to calculate the self-consistent charge and spin density of a neutral Gd atom. The calculated magnetic form factor agrees extremely well with experiment. Comparison with a paramagnetic RAPW calculation shows the procedure should be accurate and fast for general band structure determinations.

Reevaluation of x-ray atomic energy levels.

Abstract: All of the x-ray emission wavelengths have recently been reevaluated and placed on a consistent \AA{}* scale. For most elements these data give a highly overdetermined set of equations for energy level differences, which have been solved by least-squares adjustment for each case. This procedure makes "best" use of all x-ray wavelength data, and also permits calculation of the probable error for each energy difference. Photoelectron measurements of absolute energy levels are more precise than x-ray absorption edge data. These have been used to establish the absolute scale for eighty-one elements and, in many cases, to provide additional energy level difference data. The x-ray absorption wavelengths were used for eight elements and ionization measurements for two; the remaining five were interpolated by a Moseley diagram involving the output values of energy levels from adjacent elements. Probable errors are listed on an absolute energy basis. In the original source of the present data, a table of energy levels in Rydberg units is given. Difference tables in volts, Rydbergs, and milli-\AA{}* wavelength units, with the respective probable errors, are also included there.

X-Ray Fluorescence Yields, Auger, and Coster-Kronig Transition Probabilities

Abstract: The present status of the field of fluorescence yields, radiationless (Auger and Coster-Kronig) and radiative transition probabilities is summarized. Tables of experimental and theoretical results are included, and tables of "best values" of important quantities are presented.

Van der Waals Radii of Elements

Abstract: The available data on the van der Waals radii of atoms in molecules and crystals are summarized. The nature of the continuous variation in interatomic distances from van der Waals to covalent values and the mechanisms of transformations between these types of chemical bonding are discussed.