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991.
Stausholm-Møller J Kristoffersen HH Hinnemann B Madsen GK Hammer B 《The Journal of chemical physics》2010,133(14):144708
We present a systematic study of electronic gap states in defected titania using our implementation of the Hubbard-U approximation in the grid-based projector-augmented wave density functional theory code, GPAW. The defects considered are Ti interstitials, O vacancies, and H dopants in the rutile phase of bulk titanium dioxide. We find that by applying a sufficiently large value for the Hubbard-U parameter of the Ti 3d states, the excess electrons localize spatially at the Ti sites and appear as states in the band gap. At U=2.5?eV, the position in energy of these gap states are in fair agreement with the experimental observations. In calculations with several excess electrons and U=2.5?eV, all of these end up in gap states that are spatially localized around specific Ti atoms, thus effectively creating one Ti(3+) ion per excess electron. An important result of this investigation is that regardless of which structural defect is the origin of the gap states, at U=2.5?eV, these states are found to have their mean energies within a few hundredths of an eV from 0.94 eV below the conduction band minimum. 相似文献
992.
Henrik Ramebäck Annika Tovedal Ulrika Nygren Petra Lagerkvist Jonas Boson Erik Johansson Jan Johansson 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):979-983
Measurement uncertainty is an important part of a measurement result that still often is neglected. A complete combined uncertainty
budget can be calculated for non-routine measurements. However, for routine measurements, this work becomes time-consuming
since every measurement result requires an uncertainty analysis. By analysing the uncertainty on a measurement system level
in e.g. high resolution gamma spectrometry, the uncertainty analysis will be universal for a particular measurement geometry.
The problem is then reduced to implementing the combined uncertainty into measurement software. This work shows how this analysis
can be done and implemented into a commercial software for gamma spectrometric measurements. 相似文献
993.
John Andersson Henrik Shahgholian Georg S. Weiss 《Communications in Mathematical Physics》2010,296(1):251-270
We introduce a new method for the analysis of singularities in the unstable problem $$ \Delta u = -\chi_{\{u >0 \}}, $$ which arises in solid combustion as well as in the composite membrane problem. Our study is confined to points of “supercharacteristic” growth of the solution, i.e. points at which the solution grows faster than the characteristic/invariant scaling of the equation would suggest. At such points the classical theory is doomed to fail, due to incompatibility of the invariant scaling of the equation and the scaling of the solution. In the case of two dimensions our result shows that in a neighborhood of the set at which the second derivatives of u are unbounded, the level set {u = 0} consists of two C 1-curves meeting at right angles. It is important that our result is not confined to the minimal solution of the equation but holds for all solutions. 相似文献
994.
We have investigated the adsorption of molecular (gaseous) SiO2 on a clean Si(1 0 0) p(2 × 2) reconstructed surface using density functional theory based methods. The SiO2 molecule is found to be chemisorbed on various sites on the Si surface and the most energetically favourable structure is on top of the dimers. The minimum energy pathways for the various adsorption channels indicate that the reaction is barrierless in all cases. The corresponding vibrational spectrum is also calculated and the adsorbed molecules are, as expected, found to have red-shifted vibrational frequencies. The energetically favourable adsorption sites and adsorption energies are comparable to the results found for SiO. 相似文献
995.
We provide L~p-versus L~∞-bounds for eigenfunctions on a real spherical space Z of wavefront type. It is shown that these bounds imply a non-trivial error term estimate for lattice counting on Z. The paper also serves as an introduction to geometric counting on spaces of the mentioned type. 相似文献
996.
A right chain ordered semigroup is an ordered semigroup whose right ideals form a chain. In this paper we study the ideal theory of right chain ordered semigroups in terms of prime ideals, completely prime ideals and prime segments, extending to these semigroups results on right chain semigroups proved in Ferrero et al. (J Algebra 292:574–584, 2005). 相似文献
997.
Auslander conjectured that every Artin algebra satisfies a certain condition on vanishing of cohomology of finitely generated
modules. The failure of this conjecture—by a 2003 counterexample due to Jorgensen and Şega—motivates the consideration of
the class of rings that do satisfy Auslander’s condition. We call them AC rings and show that an AC Artin algebra that is left-Gorenstein is also right-Gorenstein.
Furthermore, the Auslander–Reiten Conjecture is proved for AC rings, and Auslander’s G-dimension is shown to be functorial
for AC rings that are commutative or have a dualizing complex. 相似文献
998.
999.
Henrik Stetkær 《Aequationes Mathematicae》2016,90(1):25-34
We solve Van Vleck’s functional equation on semigroups with an involution in terms of multiplicative functions. 相似文献