454 research outputs found
A World of Fields
Trope ontology is exposed and confronted with the question where one trope ends and another begins. It is argued that tropes do not have determinate boundaries, it is arbitrary how tropes are carved up. An ontology, which I call field ontology, is proposed which takes this into account. The material world consists of a certain number of fields, each of which is extended over all of space. It is shown how field ontology can also tackle the problem of determin-able properties and the problem of completeness of things
Quasiparticle Corrections to the Electronic Properties of Anion Vacancies at GaAs(110) and InP(110)
We propose a new method for calculating optical defect levels and
thermodynamic charge-transition levels of point defects in semiconductors,
which includes quasiparticle corrections to the Kohn-Sham eigenvalues of
density-functional theory. Its applicability is demonstrated for anion
vacancies at the (110) surfaces of III-V semiconductors. We find the (+/0)
charge-transition level to be 0.49 eV above the surface valence-band maximum
for GaAs(110) and 0.82 eV for InP(110). The results show a clear improvement
over the local-density approximation and agree closely with an experimental
analysis.Comment: 4 pages including 1 figure, RevTe
Investigations on the long-term radiation stability of borosilicate glasses against alpha-emitters
Low-energy electronic properties of clean CaRuO: elusive Landau quasiparticles
We have prepared high-quality epitaxial thin films of CaRuO with residual
resistivity ratios up to 55. Shubnikov-de Haas oscillations in the
magnetoresistance and a temperature dependence in the electrical
resistivity only below 1.5 K, whose coefficient is substantially suppressed in
large magnetic fields, establish CaRuO as a Fermi liquid (FL) with
anomalously low coherence scale. Non-Fermi liquid (NFL) dependence is
found between 2 and 25 K. The high sample quality allows access to the
intrinsic electronic properties via THz spectroscopy. For frequencies below 0.6
THz, the conductivity is Drude-like and can be modeled by FL concepts, while
for higher frequencies non-Drude behavior, inconsistent with FL predictions, is
found. This establishes CaRuO as a prime example of optical NFL behavior in
the THz range.Comment: 12 pages, 21 figures including supplemental materia
Quantum Monte Carlo calculations of H dissociation on Si(001)
We present quantum Monte Carlo calculations for various reaction pathways of
H with Si(001), using large model clusters of the surface. We obtain
reaction energies and energy barriers noticeably higher than those from
approximate exchange-correlation functionals. In improvement over previous
studies, our adsorption barriers closely agree with experimental data. For
desorption, the calculations give barriers for conventional pathways in excess
of the presently accepted experimental value, and pinpoint the role of coverage
effects and desorption from steps.Comment: 4 pages, 1 figur
Chemical compatibility of HLW borosilicate glasses with actinides: solubilities and segregation processes
Zur Problematik der sicheren Beseitigung α-haltiger Abfaelle aus Wiederaufarbeitung und Brennelementfertigung am Beispiel des Langzeitverhaltens hochaktiver Glaeser
Symmetric Versus Nonsymmetric Structure of the Phosphorus Vacancy on InP(110)
The atomic and electronic structure of positively charged P vacancies on
InP(110) surfaces is determined by combining scanning tunneling microscopy,
photoelectron spectroscopy, and density-functional theory calculations. The
vacancy exhibits a nonsymmetric rebonded atomic configuration with a charge
transfer level 0.75+-0.1 eV above the valence band maximum. The scanning
tunneling microscopy (STM) images show only a time average of two degenerate
geometries, due to a thermal flip motion between the mirror configurations.
This leads to an apparently symmetric STM image, although the ground state
atomic structure is nonsymmetric.Comment: 5 pages including 3 figures. related publications can be found at
http://www.fhi-berlin.mpg.de/th/paper.htm
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