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The influence of the well width fluctuations on the dependence of the binding energy of excitonic complexes in quantum wells is studied by using the path-integral Monte-Carlo technique. The results are compared with available experimental data and a good agreement is found.Postdoctoral researcher of FWO-Vlaanderen 相似文献
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W. G. Habashi G. Baruzzi M. F. Peeters M. M. Hafez 《Numerical Methods for Partial Differential Equations》1991,7(2):193-207
Finite element solutions of the Euler and Navier-Stokes equations are presented, using a simple dissipation model. The discretization is based on the weak-Galerkin weighted residual method and equal interpolation functions for all the unknowns are permitted. The nonlinearity is iterated upon using a Newton method and at each iteration the linear algebraic system is solved by a direct solver with all unknowns fully coupled. Results are presented for two-dimensional transonic inviscid flows and two- and three-dimensional incompressible viscous flows. Convergence of the algorithm is shown to be quadratic, reaching machine accuracy in very few iterations. The inviscid results demonstrate the existence of nonunique numerical solutions to the steady Euler equations. 相似文献
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Jörn Müller Helmuth Menig Gottfried Huttner Albin Frank 《Journal of organometallic chemistry》1980,185(2):251-263
The complexes [Ir(COD)(η5-C7H9)] and [Ir(COD)(η5-C8H11)] are obtained by the isoprophyl Grignard synthesis of [Ir(COD)Cl]2 (COD = η4-1,5-cyclooctadiene) in the presence of cycloheptatriene, and cyclooctatriene, respectively. The later reaction yields [IrH(COD)(δ4-1,3,6-C8H10)] as a by-product which, in contrast to other [IrH(η4-cyclodiene)2] complexes, does not show H-addition-elimination equilibria. Reduction of [Ir(1,3-C7H10)2Cl] with C2H5OH/Na2CO3 yields [Ir(η4-1,3-C7H10)](η5-C7H9)] which was characterized by X-ray analysis. [Ir(COD)Cl]2 reacts with Na2C8H8, and after hydrolysis unstable [Ir(COD)(η5-C8H9)] is formed which by protonation with HPF6 is converted into the [Ir(COD)(η6-1,3,5-C8H10)]+ cation. All these compounds are fluxional in solution. 相似文献
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Alfred Trautwein Yutaka Maeda Frank E. Harris Helmuth Formanek 《Theoretical chemistry accounts》1974,36(1):67-76
Experimental Mössbauer spectra of the Fe57-enriched CO complex of sperm whale myoglobin (MbCO) at T= 4.2 K with and without applied magnetic field (H⊥γ) were measured to derive the sign of the electric field gradient (EFG), the quadrupole splitting ΔE Q, and the isomer shift δ of the heme iron. We find a positive EFG, δE Q = 0.363 mm/sec, and δ + 0.266 mm/sec. Molecular orbital calculations were carried out to obtain theoretical estimates of EFG and ΔE Q for several steric arrangements of the CO ligand relative to the heme group. Our results are most consistent with the conclusion that the iron is situated in the heme plane, and that a bent geometry with a Fe-C-O angle of about 135 ° is more favorable than a more symmetric structure with a linear Fe-C-O geometry. 相似文献
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