X-alpha method

John Slater, bom Oak Park, Illinois, 1900. Ph.D. Harvard, 1923. Professor of physics, Harvard, 1924-1930 MIT 1930-1966 University of Florida at Gainesville, 1966-1976. Author of 14 textbooks, contributed to solid-state physics and quantum chemistry, developed X-alpha method (early density functional theory method). Died Sanibel Island, Florida, 1976. 

The DV-X Alpha Method for Design and Characterization of Materials Editors H. Adachi, T. Mukoyama, and J. Kawai... 

Dunlap, B. 1., Connolly, J. W. D., and Sabin, J. R. (1977]. Applicability of LCAO-X-alpha methods to molecules containing transition-metal atoms - nickel atom and nickel hydride, Int. J. Quantum Chem. Symp. 11,... 

Hartree-Fock-Slater Method for Materials Science. The DV-X Alpha Method for Design and Characterization of Materials, eds. H.Adachi, T.Mukoyama, J. Kawai, in Springer Series in Materials Science, vol. 84, (Spinger, Berlin, Heidelberg, New York, 2006)... 

Figure 1 A family tree of quantum chemistry DFT, density functional theory QMC, quantum Monte Carlo RRV, Rayleigh-Ritz variational theory X-a, X-alpha method KS, Kohn-Sham approach LDA, BP, B3LYP, density functional approximations VQMC, variational QMC DQMC, diffusion QMC FNQMC, fixed-node QMC PIQMC, path integral QMC EQMC, exact QMC HF, Hartree-Fock EC, explicitly correlated functions P, perturbational MP2, MP4, Maller-Plesset perturbational Cl, configuration interaction MRCI, multireference Cl FCI, full Cl CC, CCSD(T), coupled-cluster approaches. Other acronyms are defined in the text.

Because of the complexity of the polyether antibiotics tittle progress has been made in stmcture determination by the chemical degradation route. X-ray methods were the techniques most successfully applied for the early stmcture elucidations. Monensin, X206, lasalocid, lysocellin, and salinomycin were included in nineteen distinct polyether x-ray analyses reported in 1983 (190). Use of mass spectrometry (191), and H (192) and nmr (141) are also reviewed. More recently, innovative developments in these latter techniques have resulted in increased applications for stmcture determinations. Eor example, heteronuclear multiple bond connectivity (hmbc) and homonuclear Hartmann-Hahn spectroscopy were used to solve the stmcture of portimicin (14) (193). East atom bombardment mass spectrometry was used in solving the stmctures of maduramicin alpha and co-factors (58). 

In the calculations presented here, the long-range effects present in a crystal were introduced explicitly for the SCF-MO treated cluster, by surrounding it with point-ions situated at the X-ray determined atomic positions of alpha-quartz. This method has been used for the more ionic systems of alpha-NaOH, and MgO with some success and the calculations described in this paper show that it is equally applicable for semi-covalent materials. 

Nitrogen adsorption was performed at -196 °C in a Micromeritics ASAP 2010 volumetric instrument. The samples were outgassed at 80 °C prior to the adsorption measurement until a 3.10 3 Torr static vacuum was reached. The surface area was calculated by the Brunauer-Emmett-Teller (BET) method. Micropore volume and external surface area were evaluated by the alpha-S method using a standard isotherm measured on Aerosil 200 fumed silica [8]. Powder X-ray diffraction (XRD) patterns of samples dried at 80 °C were collected at room temperature on a Broker AXS D-8 diffractometer with Cu Ka radiation. Thermogravimetric analysis was carried out in air flow with heating rate 10 °C min"1 up to 900 °C in a Netzsch TG 209 C thermal balance. SEM micrographs were recorded on a Hitachi S4500 microscope. 

Sulfur can be analyzed by x-ray, GC and GC/MS techniques. Alpha-octacy-closulfur is dissolved in benzene, toluene, or chloroform and analyzed for sulfur by GC using a flame photometric detector or by GC/MS. The characteristic mass ions for its identification are multiples of 32 (i.e. 32, 64, 128, and 256). Sulfur may be identified by mixing a little powder with copper, silver, or mercury at room temperature and identifying the metal sulfide from color change and various instrumental methods. 

Heinrich, M., H. Rimpler, and N. A. Barrera. Indigenous phytotherapy of gastrointestinal disorders in a lowland Mixe community (Oaxaca, Mexico) Ethnopharmacologic evaluation. J Ethnopharmacol 1992 36(1) 63—80. Liao, Z. K., J. Jiang, and X. P. Xu. The technical method for preparation of phytic acid and oryzenin. Huaxi Yaoxue Zazhi 1996 11(1) 46-70. Tokuyama, T. 5-Alpha-reductase inhibitor from rice for therapeutic use. Patent-Japan Kokai Tokkyo Koho-07 157,436 1993 7 pp. 

Flocchini, R. G., Feeney, P. J., Sommervllle, R, J., and Cahill, T. A., Sensitivity versus target backings for elemental analysis by alpha-excited X-ray emission. Nucl. Insts. and Methods, 1972, 100, 379-402. 

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