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[en] Graphical abstract: Non-bonding degenerate systems with disjoint/non-disjoint composite bands are suggested. Regardless of the disjoint bands, these systems are predicted to be ferromagnetic due to non-trivial exchange interactions in the non-disjoint bands. Highlights: ► Non-bonding systems with disjoint/non-disjoint composite bands are suggested. ► Regardless of the disjoint bands, these systems are predicted to be ferromagnetic. ► Organic ferromagnets based on the composite bands are suggested. ► Wannier analysis and DFT calculations supported the ferromagnetic interactions. - Abstract: Non-bonding degenerate systems with disjoint/non-disjoint composite bands are suggested. In these systems, one of the non-bonding bands is disjoint, and another is non-disjoint type. Whereas the Wannier functions in the former bands span no common atoms, the Wannier functions in the latter bands span common atoms. Regardless of the disjoint bands, these systems are predicted to be ferromagnetic due to non-trivial exchange interactions in the non-disjoint bands. The ferromagnetic interactions are supported by DFT calculations.
[en] Highlights: • The exchange interaction J and the first hyperpolarizability β for DAEs were calculated. • The direction of change is always logically related to the π-conjugation pathway. • The switching directions of J and β are different for some DAEs. • The SE values of β are smaller than the SE values of J for all molecules. • Oxidizing the sulfur atoms of the DAEs yields small variations on SE of J and β. We have calculated the exchange interaction J and the first hyperpolarizability β for photochromic diarylethenes (DAEs), 5,5′-diphenyl-di(3-thienyl)ethene 1, 5,5′-diphenyl-di(2-thienyl)ethene 2, 2,5-diphenyl-di(3-thienyl)ethene 3, and their corresponding oxidized derivatives. The switching direction of DAE 2 is found to be opposite from DAE 1. The switching direction of DAE 3 is opposite from DAE 1 for J, but not for β. For all molecules, the switching efficiency (SE) values of β are smaller than those of J. Oxidizing the sulfur atoms yields rather small variations on SEs of J and β. The non-trivial structure-property relationships for J and β are rationalized.
[en] We report our investigation on the octet baryon spectrum in the nonrelativistic quark model by taking into account the two-gluon exchange effect. The calculated octet baryon masses agree better with the experimental data. It is also shown that the two-gluon exchange interactions bring a significant correction to the Gell-Mann - Okubo mass formula. (authors)
[en] Systematic studies of electrical transport properties of (Co1-xInx)2O3-v concentrated ferromagnetic semiconductors were performed. Quantitative analysis demonstrated that spin dependent variable range hopping dominated the low temperature transport behavior. Moreover, it was found that ferromagnetic or antiferromagnetic coupling of electron-hole pair generated during the variable range hopping process is responsible for the negative or positive magnetoresistance, respectively. Our results not only illustrate the connection between magnetoresistance and electron-hole exchange interaction but also provide a unique method to detect the exchange interaction of electron-hole pair
[en] Previously we derived an expression for the crystalline potential V2 induced by magnetostriction in the RFe2 series, using the assumption, generally accepted at the time, that /lambda100/<111/. This assumption has now been shown to be unfounded. We therefore derive new expressions for V2, which are valid whatever lambda100 and lambda111
[en] Highlights: • Gaussian-based and erfc short-range potentials for perturbation theory. • Gaussian short-range potential yields better similarity to the bare potential. • Gaussian cutoff reproduces the HF and MP2 methods well. A Gaussian-based range-separation approach is applied to the Hartree–Fock exchange interaction and the second-order perturbation theory, comparing the results with those provided through the erfc short-range potential approach. The Gaussian short-range potential's behavior resembles more that of the bare 1/r potential than that of the erfc short-range potential around the origin. Thus, the Gaussian-based range-separation of the exchange term agrees better with the ordinary HF method and the Møller–Plesset perturbation theory.