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1.
S. Onari T. Hiroaki A. Ono S. Hidaka T. Arai T. Mori 《International Journal of Infrared and Millimeter Waves》1989,10(7):737-744
Systematic measurements of the far infrared reflection spectra of high Tc superconductors LnBa2Cu3Ox for various Ln as shown in the title were performed. Infrared reflection spectra of tetragonal LnBa2Cu3Ox exhibit Reststrahlen vibration near 640, 590, 530, 355 and 250 cm–1, common to these materials, and the spectra of the orthorhombic LnBa2Cu3Ox exhibit the characteristics of free carriers except PrBa2Cu3Ox with weak phonon structures near 617, 570, 317 and 285 cm–1. PrBa2Cu3Ox is not a superconductor, and it has no characteristic broad band due to free carriers for all x in the range of 6 to 7. Lattice dynamical calculation was performed by the use of the shell model and the calculated results express quite well the characteristic features of infrared experiments. 相似文献
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K. Matsuishi T. Anzaki S. Onari T. Arai 《International Journal of Infrared and Millimeter Waves》1989,10(7):745-750
Far infrared absorption spectra of amorphous (As2S3)1–x(Sb2S3)x system (x=0.00.6) were measured in the wavenumber region 725 cm–1 with Lamellar grating far infrared Fourier Transform Spectrometer, and the spatial fluctuation of charges and its correlation range were estimated with charge fluctuation model. The charge fluctuation of (As2S3)1–x(Sb2S3)x system increases with Sb2S3 concentration x. On the other hand, the correlation length of the charge fluctuation decreases from 7 A to 4.5 A with an increase in x. As a result, it can be found that the medium range order of As2S3 changes drastically with an incease in Sb2S3 concentration x. 相似文献
3.
Raman scattering spectra on a layer type compound 3RNbS2 were measured at 300 and 77 K, and three peaks were observed at 382, 325 and 281 cm?1 at 300 K. The vibration modes were analyzed in terms of Bromley's nearest neighbour model, and a good agreement with the experiment was obtained. 相似文献
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Hiroko X. Kondo Ayumi Kusaka Colin K. Kitakawa Jinta Onari Shusuke Yamanaka Haruki Nakamura Yu Takano 《Journal of computational chemistry》2019,40(23):2043-2052
Hydrogen-bond (H-bond) interaction energies in α-helices of short alanine peptides were systematically examined by precise density functional theory calculations, followed by a molecular tailoring approach. The contribution of each H-bond interaction in α-helices was estimated in detail from the entire conformation energies, and the results were compared with those in the minimal H-bond models, in which only H-bond donors and acceptors exist with the capping methyl groups. The former interaction energies were always significantly weaker than the latter energies, when the same geometries of the H-bond donors and acceptors were applied. The chemical origin of this phenomenon was investigated by analyzing the differences among the electronic structures of the local peptide backbones of the α-helices and those of the minimal H-bond models. Consequently, we found that the reduced H-bond energy originated from the depolarizations of both the H-bond donor and acceptor groups, due to the repulsive interactions with the neighboring polar peptide groups in the α-helix backbone. The classical force fields provide similar H-bond energies to those in the minimal H-bond models, which ignore the current depolarization effect, and thus they overestimate the actual H-bond energies in α-helices. © 2019 The Authors. Journal of Computational Chemistry published by Wiley Periodicals, Inc. 相似文献
6.
We study the effect of local impurity and the neutron scattering spectrum based on the five-orbital model obtained by the first principle calculation for iron pnictides. We find that the interband impurity scattering is induced by the complex multiorbital structure. This fact means that the fully-gapped sign-reversing s-wave state, which is predicted by spin-fluctuation theories, is very fragile against impurities. The result suggests a reasonable possibility that the fully-gapped s-wave state without sign reversal (s++-wave) would be realized in dirty iron pnictides. We also find that broad peak structure observed in the neutron scattering measurements can be explained by the s++-wave state. 相似文献
7.
Yuichiro Shimokaji Seiichiro Onari Kazumasa Miyake 《Journal of Physics and Chemistry of Solids》2008,69(12):3280-3282
It is an important issue to clarify whether the odd-frequency superconducting state can be derived from microscopic Hamiltonian or not, where gap function has an odd-parity in frequency. We study the instability of following four superconducting states: (1) even-frequency spin-singlet, (2) even-frequency spin-triplet, (3) odd-frequency spin-singlet and (4) odd-frequency spin-triplet. By using the fluctuation exchange (FLEX) approximation on a triangular and square lattice, we find that the odd-frequency spin-triplet pairing can become dominant at a certain region where the suppression of the antiferromagnetic fluctuation due to a geometric frustration becomes prominent. 相似文献
8.
K. Shigeta S. Onari K. Yada Y. Tanaka 《Physica C: Superconductivity and its Applications》2009,469(15-20):988-990
We study the superconductivity in the Hubbard model on quasi-one-dimensional triangular lattice using random phase approximation (RPA). We find that odd-frequency spin-singlet p-wave pairing can be realized on isosceles quasi-one-dimensional triangular lattice. 相似文献
9.
The relative cross sections for one-phonon scattering at the E1 resonance have been measured for several cubic semiconductors. Using the dielectric theory of the Raman tensor and the values of the real and imaginary parts of the dielectric constant determined from optical measurements we are able to obtain relative values for the intraband deformation potential of the valence bands d53,0. Taking d53,0 = 1 for Ge we find the values 2.4, 1.0, 0.42, 0.64 and 1.1 for Si, GaAs, Mg2Si, Mg2Ge, and Mg2Sn, respectively. 相似文献
10.
The temperature dependence of the phonon absorption band of MnTe, 154 cm?1, is investigated and an anomalously large shift is observed near the Néel temperature. The frequency variation due to the volume change and the magnetic terms are estimated, the latter fraction being not less than ca. 40%. 相似文献