38,764 research outputs found
Promising ferrimagnetic double perovskite oxides towards high spin polarization at high temperature
We predict through our first-principles calculations that four double
perovskite oxides of Bi2ABO6 (AB = FeMo, MnMo, MnOs, CrOs) are half-metallic
ferrimagnets. Our calculated results shows that the four optimized structures
have negative formation energy, from -0.42 to -0.26 eV per formula unit, which
implies that they could probably be realized. In the case of Bi2FeMoO6, the
half-metallic gap and Curie temperature are predicted to reach to 0.71 eV and
650 K, respectively, which indicates that high spin polarization could be kept
at high temperatures far beyond room temperature. It is believed that some of
them could be synthesized soon and would prove useful for spintronic
applications.Comment: 4 pages, 3 figure
A hybrid representation based simile component extraction
Simile, a special type of metaphor, can help people to express their ideas more clearly. Simile component extraction is to extract tenors and vehicles from sentences. This task has a realistic significance since it is useful for building cognitive knowledge base. With the development of deep neural networks, researchers begin to apply neural models to component extraction. Simile components should be in cross-domain. According to our observations, words in cross-domain always have different concepts. Thus, concept is important when identifying whether two words are simile components or not. However, existing models do not integrate concept into their models. It is difficult for these models to identify the concept of a word. What’s more, corpus about simile component extraction is limited. There are a number of rare words or unseen words, and the representations of these words are always not proper enough. Exiting models can hardly extract simile components accurately when there are low-frequency words in sentences. To solve these problems, we propose a hybrid representation-based component extraction (HRCE) model. Each word in HRCE is represented in three different levels: word level, concept level and character level. Concept representations (representations in concept level) can help HRCE to identify the words in cross-domain more accurately. Moreover, with the help of character representations (representations in character levels), HRCE can represent the meaning of a word more properly since words are consisted of characters and these characters can partly represent the meaning of words. We conduct experiments to compare the performance between HRCE and existing models. The experiment results show that HRCE significantly outperforms current models
Assessment of density functional methods with correct asymptotic behavior
Long-range corrected (LC) hybrid functionals and asymptotically corrected
(AC) model potentials are two distinct density functional methods with correct
asymptotic behavior. They are known to be accurate for properties that are
sensitive to the asymptote of the exchange-correlation potential, such as the
highest occupied molecular orbital energies and Rydberg excitation energies of
molecules. To provide a comprehensive comparison, we investigate the
performance of the two schemes and others on a very wide range of applications,
including the asymptote problems, self-interaction-error problems, energy-gap
problems, charge-transfer problems, and many others. The LC hybrid scheme is
shown to consistently outperform the AC model potential scheme. In addition, to
be consistent with the molecules collected in the IP131 database [Y.-S. Lin,
C.-W. Tsai, G.-D. Li, and J.-D. Chai, J. Chem. Phys., 2012, 136, 154109], we
expand the EA115 and FG115 databases to include, respectively, the vertical
electron affinities and fundamental gaps of the additional 16 molecules, and
develop a new database AE113 (113 atomization energies), consisting of accurate
reference values for the atomization energies of the 113 molecules in IP131.
These databases will be useful for assessing the accuracy of density functional
methods.Comment: accepted for publication in Phys. Chem. Chem. Phys., 46 pages, 4
figures, supplementary material include
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