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Showing papers by "Pacific Northwest National Laboratory published in 1978"


Journal ArticleDOI
TL;DR: In this paper, the authors extended the HONDO ab initio polyatomic SCF program to the analytic computation of energy gradients, where the Hellmann-Feynman theorem is not assumed, and all two-electron contributions to the gradient are included explicitly.
Abstract: Symmetry methods employed in the HONDO ab initio polyatomic SCF program are extended to the analytic computation of energy gradients Validity of the Hellmann–Feynman theorem is not assumed, ie, all two‐electron contributions to the gradient are included explicitly The method is geared to the efficient computation of entire blocks of two‐electron integrals Just one of a set of symmetrically related blocks must be computed The gradient contribution from each unique block is multiplied by q4, the number of equivalent blocks, and added into a ’’skeleton gradient vector,’’ all other blocks are simply omitted After processing molecular integrals, the true gradient vector is generated by projecting the symmetric component out of the skeleton vector The analysis is based on Eqs (26) and (33) which are valid for many variational wavefunctions including restricted closed shell and unrestricted open shell self‐consistent field functions We also extend the use of translational symmetry proposed previously b

221 citations



Journal ArticleDOI
TL;DR: The concentrations of 43 major, minor, and trace elements were measured by x-ray fluorescence, atomic absorption, and instrumental neutron activation for nine well-defined size fractions, with mass median diameters of 0.5 to 50 µm, of fly ash from a western coal-fired steam plant.
Abstract: The concentrations of 43 major, minor, and trace elements were measured by x-ray fluorescence, atomic absorption, and instrumental neutron activation for nine well-defined size fractions, with mass median diameters of 0.5 ..mu.. to 50 ..mu..m, of fly ash from a western coal-fired steam plant. There was generally good agreement in concentrations of elements analyzed by more than one technique. Concentration profiles as a function of mean particle size were established for various elements. Based on the concentration profiles, the elements can be divided into three distinct groups. One group consists primarily of the volatile elements or elements partially volatilized during coal combustion (examples include As, Se, Zn, Ga, etc.), and their concentrations decrease with increasing particle size. A second group, which shows a minor or direct dependence on particle size, as in the case of Si, is apparently associated primarily with the fly-ash matrix. The last group of elements, which includes Ca, Sr, Y, and the rare earths, shows small changes in their concentration profiles with a maximum in concentration at approximately 5 ..mu..m. 6 tables, 6 figures.

128 citations


Journal ArticleDOI
TL;DR: In this paper, a consistent experimental and theoretical view for the structure of the ethyl radical was presented and it was shown that the stable conformation is the staggered form and that the CH3 group in the radical is distorted.
Abstract: A consistent experimental and theoretical view is presented for the structure of the ethyl radical. These results show that the stable conformation is the staggered form and that the CH3 group in the radical is distorted.

65 citations


Journal ArticleDOI
TL;DR: In this article, the ground electronic state of B2 is of 3Σ−g symmetry, and the Douglas-Herzberg emission system near 3200 A is due to transitions from the second 3 Σ−u state to the X ε 3 ε−g state.
Abstract: An accurate ab initio configuration interaction calculation has established that the ground electronic state of B2 is of 3Σ−g symmetry, and that the Douglas–Herzberg emission system near 3200 A is due to transitions from the second 3Σ−u state to the X 3Σ−g state. The lowest 5Σ−u state, suggested by previous calculations as the ground state, is found to lie about 1300 cm−1 above the X 3Σ−g state. The assignment of the Douglas–Herzberg transition is based on the close agreement between calculated and observed molecular constants which, with observed values in parentheses, are Re(3Σ−g) =1.622(1.590) A, ωe(3Σ−g) =988.5(1035.2) cm−1, Re(2 3Σ−u) =1.660(1.625) A, ωe(2 3Σ−u) =884.5(929.3) cm−1, and Te(2 3Σ−u) =31 438(30 546.1) cm−1. Further support for this assignment is seen in the close agreement between calculated and observed isotope shifts and intensity distributions. An explanation is given for why the 1 3Σ−u −X 3Σ−g transition has not been observed.

54 citations


Journal ArticleDOI
01 Aug 1978-Fuel
TL;DR: In this paper, the difficulty of extracting meaningful information from reductive alkylation experiments on low-rank coals is considered, and the difficulty is also discussed in the context of lowrank coal coals.

19 citations



Journal ArticleDOI
TL;DR: In this article, the authors describe Resonance ionization spectroscopy for precision measurements of the diffusion of reactive atoms in gaseous media, and show that Cs atoms in an Ar-CH4 mixture can be used to test a rigorous solution to the diffusion equation.

12 citations



Journal ArticleDOI
TL;DR: Pre-exposure treatment of rats with a radioprotective agent, WR2721 (S-2-aminopropylamino)ethyl phosphorothioic acid hydrate reduced edema formation, as measured by leakage of serum protein into the air spaces, and acute mortality.

9 citations


Journal ArticleDOI
TL;DR: A review of the metallurgical characterization techniques used at Battelle Northwest for coatings made by high-rate sputter deposition methods is given in this paper, which includes specific examples and a discussion of problems encountered during characterization.

Journal ArticleDOI
TL;DR: In this article, a new type of pressure-crossflow solution method is developed for solving the fluid conservation equations used by the COBRA-IIIC code, which is extremely efficient from a numerical point of view, and offers sizeable reductions in running time, relative to conventional numerical schemes for predicting the fluid flow and enthalpy distributions in nuclear reactor fuel rod bundles and reactor cores.

Proceedings ArticleDOI
17 Nov 1978
TL;DR: In this paper, a technique using Fourier transform analysis which is suitable for measuring the specularity of solar glass components in the mrad and sub-mrad is discussed and demonstrated.
Abstract: A technique using Fourier transform analysis which is suitable for measuring the specularity of solar glass components in the mrad and sub-mrad is discussed and demonstrated. A brief mathematical background as well as illustrative examples are included. A number of methods for image analysis are discussed with particular emphasis given to electronic integrating detectors. Typical Fourier plane image distributions are given for a few common solar utilization materials and details of the instrument used to produce the images are considered. The limitations and capabilities of various instruments are outlined along with methods for further enhancing the utility and sensitivity of the technique.

Journal ArticleDOI
TL;DR: In this article, the brominated derivative of polymeric, sulfur nitride, (SN)/sub x/ (SN/sub x)/(SN)/ sub x/ has been previously found to produce a noncyclic (SN)-sub 4/ species upon sublimation.
Abstract: The occurrence of surface related reactions in mass spectrometer ion sources has long been recognized. The products of gas--surface reactions, involving surface ionization on the filament and pyrolysis on hot surfaces, often contribute minor peaks to electron impact (EI) mass spectra, and complications can be severe in the analysis of reactive or thermally unstable compounds. The resulting mass spectra may lead to an assumption of the presence of impurities not actually in the sample, or even cause errors in the identification of unknown compounds and mixtures. The purpose of this correspondence is to present an example of such surface related phenomena and to point out how these problems may be avoided utilizing chemical ionization (CI) mass spectrometry. The compound used to illustrate this problem is the brominated derivative of polymeric, sulfur nitride, (SN)/sub x/. (SN)/sub x/ has been previously found to produce a noncyclic (SN)/sub 4/ species upon sublimation. The brominated derivative, of empirical formula SNBr/sub 0/./sub 4/, was expected to yield (SN)/sub 4/ plus an unknown brominated species upon sublimation; hence, identification of the bromine containing species was of particular interest. Results show that argon (in the absence of a large water impurity) offers a distinct advantage for themore » analysis of mixtures over more commonly used methane, isobutane, and ammonia as a CI reagent. The latter involve relatively low energy proton transfer processes; hence, molecular species such as Br/sub 2/ and S/sub 8/ are not ionized by isobutane and NH/sub 3/ CI. Charge transfer from argon ions (Ar/sup +/ and Ar/sub 2//sup +/ are the major reagent ions in this work) is a much higher energy process and is capable of ionizing most molecules. (JRD)« less