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11.
Using the approach of Rulla (1996 SIAM J. Numer. Anal. 33, 68-87)for analysing the time discretization error and assuming moreregularity on the initial data, we improve on the error boundderived by Barrett and Blowey (1996 IMA J. Numer. Anal. 16,257-287) for a fully practical piecewise linear finite elementapproximation with a backward Euler time discretization of amodel for phase separation of a multi-component alloy. 相似文献
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The synthesis of multivalent neoglycoconjugates with 2,6-diamino-2,6-dideoxyglucose is accomplished by a flexible Ugi multicomponent approach leading to mono-, di- and tri-valent carbohydrate clusters. 相似文献
15.
Some phonon dispersion curves in ZnO have been determined by inelastic neutron scattering. Shell model calculations with 10 parameters were fitted to the neutron data, to optical frequencies and to dielectric constants. Good agreement was obtained including some elastic constants which were calculated from the model. 相似文献
16.
D. Wagner D. Bäuerle F. Schwabl B. Dorner H. Kraxenberger 《Zeitschrift für Physik B Condensed Matter》1980,37(4):317-320
The temperature and concentration dependence of the soft zone boundary mode in heavily reduced SrTiO3 was studied by means of inelastic neutron scattering. It was found that the 105 K structural phase transition is suppressed completely for about 2% oxygen vacancies. The results are discussed in terms of recent models. 相似文献
17.
The cross section of the coherent, inelastic neutron scattering is characteristically decreased in the presence of defect-induced lattice distortions. This effect is in analogy to the attenuation of Bragg intensities due to a static Debye-Waller factor. The integrated scattering intensities from transversal acoustic (TA-) phonons of the system NbN0.014 have been measured and are shown to be attenuated with respect to the scattering intensities from the phonons of a pure Nb crystal. We discuss the obtained results through comparison with various model calculations. 相似文献
18.
Th. Brueckel B. Dorner A. G. Gukasov V. P. Plakhty W. Prandl E. F. Shender O. P. Smirnow 《Zeitschrift für Physik B Condensed Matter》1988,72(4):477-485
The Fe3+ ions in the garnet Ca3Fe2Ge3O12 form two identical antiferromagnetic subsystems. The interaction between the two subsystems is vanishing within molecular field approximation forq=0. A coupling appears due to the spin fluctuations. The dynamics of the system is described by the Hamiltonian for a Heisenberg antiferromagnet. Symmetry requirements impose two exchange parameters between the sublattices (nearest neighbours)J
1 in the direction of the 3-fold axis andJ'
1 in the other three space diagonals. The interaction within each sublattice (second nearest neighbours) is described by the exchange parameterJ
2. The measured spin wave dispersion curves for the three principal symmetry directions are very well reproduced by a model calculation withJ
1=-0.909(9) K,J'
1=-0.307(8) K andJ
2=-0.615(2)K. The observed intensities are in agreement with predictions from the model. Forq0 the model predicts two acoustic branches going towards zero frequency. A calculation beyond linear spin wave theory forq=0 predicts a quantum gap for the lower acoustic branch. This gap has been found at 0.033(4) THz. An anisotropy gap of 0.007 THz has been taken from the literature. 相似文献
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