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141.
Non-equilibrium molecular dynamics simulations have been performed to
investigate the effect of the cross-section shape on the thermal
conductivity of argon nanowires. Some typical cross-section shapes,
such as triangle, square, pentagon, hexagon and circle, are carefully
explored. The simulation results show that with the same
cross-sectional area of the regular polygons, the thermal
conductivities decrease with the reduction of the sides of the
polygons, and the thermal conductivity of the circular nanowire is
larger than those of the other polygonal ones. Phonon gas kinetic
theory is used to analyse the phonon transport in nanowires, and the
concept of equivalent diameter is proposed to illustrate the
characteristic dimension of the none-circular cross-section. 相似文献
142.
Based on a force constant model, we investigated the phonon spectrum and then specific heat of single-walled boron nitride nanotubes. The results show that the frequencies of Raman and infrared active modes decrease with increasing diameter in the low frequency, which is consistent with the results calculated by density functional theory. The fitting formulae for diameter and chirality dependence of specific heat at 300K are given. 相似文献
143.
This paper shows that exact calculation for transition probability can make some systems deviate fromFermi golden rule seriously. This paper also shows that the corresponding exact calculation of hopping rate inducedby phonons for deuteron in Pd-D system with the many-body electron screening, proposed by Ichimaru, can explainthe experimental fact observed in Pd-D system, and predicts that perfection and low-dimension of Pd lattice are veryimportant for the phonon-induced hopping rate enhancement in Pd-D system. 相似文献
144.
测量了 ZBL AN玻璃中 Pr3 ,Pr3 Yb3 的吸收光谱和 Pr3 的荧光发射波长 .分析了 Pr3 / Yb3 共掺光纤放大器中的能量转移过程 ,运用电多极子理论和多声子辅助能量转移理论计算了 Pr3 和 Yb3 之间的能量转移几率 .对离子掺杂浓度 ,泵浦波长对 Pr3 和 Yb3 之间能量转移的影响进行了讨论 ,得到了最佳掺杂浓度和泵浦波长 .此时 Pr3 / Yb3 共掺的光纤放大器具有最大的荧光强度和最高的增益 . 相似文献
145.
Erratum to “Designing thermal demultiplexer: Splitting phonons by negative mass and genetic algorithm optimization”
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Yu-Tao Tan 《中国物理 B》2021,30(9):99902-099902
Equations (8) and (9) in the original paper [Chin. Phys. B 30 036301 (2021)] are corrected. 相似文献
146.
考虑了Amide-Ⅰ振子同肽群振动的光学声子相耦合,在该理论中研究了在蛋白质分子中的孤立子引起的红外吸收的反常红移和温度依赖关系。所得结果较好地吻合于实验值。从而也证实了蛋白质中确有孤立子激发的存在 相似文献
147.
148.
D. Rönnow L.F. Lastras-Martínez M. Cardona 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(1):29-35
Within the past years the optical excitations of electrons have been measured for semiconductor samples of different isotope
compositions. The isotope shift observed have been compared with calculations of the effects of electron-phonon interaction
on the electronic band structure. While qualitative agreement has been obtained, some discrepancies remain especially concerning
the E1 and transitions. We have remeasured the effect of isotope mass on the E1 and transitions of germanium with several isotopic compositions. The results, obtained by means of spectroscopic ellipsometry,
confirm that the real part of the gap self-energies induced by electron-phonon interaction is larger than found from band
structure calculations, while the imaginary part agrees with those calculations, which are based on a pseudopotential band
structure and a bond charge model for the lattice dynamics. Our results agree with predictions based on the measured temperature
dependence of the gaps. We compare our data for E1 and with results for the lowest direct (E0) and indirect (Eg) gaps. The measured values of and increase noticeably with increasing isotope mass. Similar effects have been observed in the temperature dependence of in and . A microscopic explanation for this effect is not available.
Received: 6 March 1998 / Revised: 27 April 1998 /
Accepted: 15 May 1998 相似文献
149.
S.W.H. Eijt R. Currat J.E. Lorenzo P. Saint-Grégoire B. Hennion Y.M. Vysochanskii 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(2):169-178
The low frequency lattice dynamics and its relationship to the second order paraelectric-to-ferroelectric transition in Sn2P2S6 is studied. The dispersion branches of the acoustic and lowest lying optical phonons in the a*-c* plane have been obtained in the ferroelectric phase, for x-polarized phonons. Close to the phase transition a considerable softening is found for the lowest optical mode (Px), comparable to the behaviour observed in previous Raman investigations. As found previously in Sn2P2Se6, a strong coupling between the TO(Px) and TA(uxz) phonons is observed, although, apparently, not strong enough to lead to an incommensurate phase. The soft TO(Px) mode at the zone center is observed. The temperature dependence of its frequency and damping shows that the transition is
not entirely displacive. At low temperatures an unusual apparent negative LO-TO splitting is observed which is shown to arise
from the coupling of the x-polarized soft mode to the nearby z-polarized optical phonon. For comparison, the soft TO(Px) dispersion in the a*-b* plane is measured in both the paraelectric and ferroelectric phases. Consistent frequency changes and LO-TO splitting are
observed, revealing a significant interaction between the TA(uyx) and LA(uxx) acoustics branches and the TO and LO soft optic branches, respectively. In contrast, the nearby y-polarized optic branch shows almost no temperature dependence. Finally, the influence of piezoelectric effects on the limiting
acoustic slopes in the ferroelectric phase is discussed.
Received: 11 May 1998 / Revised and Accepted: 15 June 1998 相似文献
150.