JaLCDOI 10.18926/20011
フルテキストURL Mem_Fac_Eng_OU_29_1_7.pdf
著者 Hiroyuki Tachibana| 東辻 浩夫| 奈良 重俊| 東辻 千枝子|
抄録 Effects of interface fluctuations on the electronic states in semiconductor quantum dots are analyzed on the basis of numerical solutions for ground state wave functions and energy eigenvalues. It is shown that the effective volume of confinement becomes smaller than the real volume of quantum dots due to fluctuation. This effect comes from the fact that the wave functions with larger characteristic wavelength are not able to deform themselves following the fluctuation of interfaces exactly.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1994-11-30
29巻
1号
開始ページ 7
終了ページ 14
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002310741
JaLCDOI 10.18926/19674
フルテキストURL Mem_Fac_Eng_OU_33_2_71.pdf
著者 鶴田 健二| 東辻 浩夫| 東辻 千枝子|
抄録 A parallel tight-binding molecular dynamics with an order-N [O(N))] algorithm is implemented to perform large-scale simulation of nanostructured materials. The algorithm is based on the Fermi-operator expansion of an electronic energy and force, and we present its basic formalisms. Accuracy necessary for molecular-dynamics simulations can be obtained by a proper truncation in the expansion. Parallel efficiency on a parallel PC cluster shows nearly ideal scaling behavior with respect to the number of processors. Applicability of the method to a silicon-carbide system is examined.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1999-04-27
33巻
2号
開始ページ 71
終了ページ 77
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002309027
JaLCDOI 10.18926/19673
フルテキストURL Mem_Fac_Eng_OU_33_2_61.pdf
著者 東辻 浩夫| 鶴田 健二| 東辻 千枝子|
抄録 The behavior of multicomponent plasmas in the Penning-Malmberg traps is discussed with the parameters corresponding to experiments with antiprotons and cryogenic electrons. The relaxation times for the energy transfer antiprotons to electrons and between parallel and perpendicular components of electrons are estimated. It is shown that, depending on the values of parameters, both the former and the latter can be the bottleneck in the cooling process.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1999-04-27
33巻
2号
開始ページ 61
終了ページ 69
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002309106
JaLCDOI 10.18926/19671
フルテキストURL Mem_Fac_Eng_OU_33_2_51.pdf
著者 東辻 浩夫| 鶴田 健二| 東辻 千枝子|
抄録 Density functional molecular dynamics method is applied to hydrogen plasma in the domain of liquid metallic hydrogen. Tentative results for the proton-proton pair distribution function and the electron-proton pair distribution function are obtained. It is shown that with the increase of the parameter γ(s), we have increasingly strong screening of proton charge by electrons and the decrease of electron density in the domain between protons.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1999-04-27
33巻
2号
開始ページ 51
終了ページ 59
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002309192
JaLCDOI 10.18926/19636
フルテキストURL Mem_Fac_Eng_OU_32_23.pdf
著者 東辻 浩夫| 岸本 篤也| 東辻 千枝子|
抄録 Parameters characterizing the structure ot confined Yukawa system are estimated for 'dusty plasmas', clouds of charged macroscopic particles formed near the boundary between plasma and the sheath and leviated by negatively biased electrode. When we have dust particles with different ratios of charge to mass, they form a two-dimensional Yukawa mixture or separate two-dimensional one-companent Yukawa systems, depending on the charge density in the sheath and number density of dust particles. In order to provide a basis for numerical simulations on Yukawa mixtures including Coulombic case, we summarize mathematical expressions necessary for molecular dynamics.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1998-04-20
32巻
1-2号
開始ページ 23
終了ページ 41
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002309150
JaLCDOI 10.18926/17833
フルテキストURL Mem_Fac_Eng_OU_43_27.pdf
著者 東辻 浩夫|
抄録 When the Coulomb coupling between fine particles becomes sufficiently strong in fine particle plasmas, the isothermal compressibility of the whole system diverges and we have a phase separation and an associated critical point. Experimental conditions of fine particle plasmas, densities and temperatures of components and the fine particle size, are obtained corresponding to characteristic parameters around the critical point and the dependency on ion species and other factors is discussed.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2009-01
43巻
開始ページ 27
終了ページ 31
ISSN 1349-6115
言語 English
論文のバージョン publisher
NAID 120002308947
JaLCDOI 10.18926/17831
フルテキストURL Mem_Fac_Eng_OU_43_22.pdf
著者 東辻 浩夫| Chai Hong| 東辻 千枝子| 鶴田 健二|
抄録 For the transfer of quantum information and the creation of entangled states, the application of tuned spin chains, systems of spins with the nearest-neighbor coupling tuned so as to give high efficiency, has been proposed and some examples of high performance have been given by several authors. In this article, the effect of deviations from tuned values and the effect of resultant asymmetry are investigated through numerical simulations and theoretical analyses. It is shown that there exists a system where the transfer efficiency is comparable with exactly tuned ones and, at the same time, robust to noises in the coupling constants. It is also shown that the effect of asymmetry on the efficiency of entanglement creation is of the second order when the asymmetry is small.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2009-01
43巻
開始ページ 22
終了ページ 26
ISSN 1349-6115
言語 English
論文のバージョン publisher
NAID 120002308966
JaLCDOI 10.18926/17829
フルテキストURL Mem_Fac_Eng_OU_43_16.pdf
著者 Kurose Tomoyuki| 鶴田 健二| 東辻 千枝子| 東辻 浩夫|
抄録 The finite-difference time-domain (FDTD) method has been applied to the calculation of the phonon band structure of two-dimensional (2D) phononic crystals, consisting of metal cylinders placed periodically in liquid. By comparing several combinations of materials for metal cylinder and liquid, we analyze the dependence of the band structures on sound speed and density of liquid media. Moreover, the negative refraction of the acoustic waves is observed at the interfaces between phononic crystal slab and the liquid. We find that an acoustic“lens effect”with the slab appears due to the negative refractions. The relationship between the focal intensity in the lens effect and the band structure is discussed.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2009-01
43巻
開始ページ 16
終了ページ 21
ISSN 1349-6115
言語 English
論文のバージョン publisher
NAID 120002308928
JaLCDOI 10.18926/17826
フルテキストURL Mem_Fac_Eng_OU_43_8.pdf
著者 Umeda Ryosuke| 東辻 千枝子| 鶴田 健二| 東辻 浩夫|
抄録 Metamaterial which has negative permittivity and permeability is investigated via computer simulations. Effects of the nanostructure on dielectric and magnetic properties of the material are taken into account by introducing the Drude-Lorentz model in the materials dispersion. We include multi-band process in the dielectric response in order to reproduce accurately experimental values of bulk Au thin film. Size effect on the dispersion is examined by comparing the model with that of a noble metal particle. Based on the dispersion model constructed, we analyze the electromagnetic response of nanostructured metamaterials to evanescent waves at microwave and optical frequencies via finite-difference time-domain simulatioins on parallel computer. A re- focusing and an amplification of the evanescent waves propagating through a metamaterial, consisting of metal slab/vacuum stacking, is demonstrated for the frequencies of 30GHz and 744THz.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 2009-01
43巻
開始ページ 8
終了ページ 15
ISSN 1349-6115
言語 English
論文のバージョン publisher
NAID 120002308833
著者 東辻 浩夫| Ishikura Satoshi| Takayama Norihisa|
発行日 1991-03-28
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
25巻
2号
資料タイプ 紀要論文
著者 東辻 浩夫|
発行日 1991-03-28
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
25巻
2号
資料タイプ 紀要論文
JaLCDOI 10.18926/15497
フルテキストURL Mem_Fac_Eng_OU_24_2_41.pdf
著者 東辻 浩夫|
抄録 A possibility to control the microscopic superconducting channel based on the proximity effect is theoretically shown by a simple one-dimensional analysis of de Gennes' equation for the order parameter.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1990-03-29
24巻
2号
開始ページ 41
終了ページ 47
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002307289
JaLCDOI 10.18926/15490
フルテキストURL Mem_Fac_Eng_OU_25_1_51.pdf
著者 東辻 浩夫|
抄録 The superconductivity proximity effect in the dirty limit is revisited and equations and boundary conditions are obtained for the case of inhomogeneous media with continuously varying characteristic parameters.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1990-12-14
25巻
1号
開始ページ 51
終了ページ 57
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002307188
JaLCDOI 10.18926/15482
フルテキストURL Mem_Fac_Eng_OU_24_1_93.pdf
著者 東辻 浩夫| 畑谷 光輝|
抄録 Propagation of charged carriers in semiconductor superlattices is analyzed on the basis of the effective mass approximation with appropriate boundary conditions at heterojunctions taken into account. Applying the finite element method, clarified are the effects of details of the potential profile, such as linear and smooth gradings and random fluctuations, on characteristics of superlattices which are expected to work as collector barriers and energy filters in electronic devices.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1989-11-29
24巻
1号
開始ページ 93
終了ページ 105
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002307513
JaLCDOI 10.18926/15468
フルテキストURL Mem_Fac_Eng_OU_23_1_69.pdf
著者 東辻 浩夫| Takei Makoto|
抄録 The statistical properties of two-dimensional systems of charges in semiconductor superlattices are analyzed and the dispersion relation of the plasma oscillation is calculated. The possibility to excite these oscillations by applying the electric field parallel to the structure is discussed.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1988-11-22
23巻
1号
開始ページ 69
終了ページ 82
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002307988
JaLCDOI 10.18926/15460
フルテキストURL Mem_Fac_Eng_OU_28_2_45.pdf
著者 東辻 浩夫| 橋本 成仁| 奈良 重俊|
抄録 Difficulties in simulating systems composed of classical and quantum particles lie in the treatment of the many-body interactions between quantum particles and the geometrical variety of configurations of classical particles. In order to overcome these difficulties, we have developed some numerical methods and applied them to simple cases. As for stationary states, the finite element method provides us with sufficient geometrical freedom. Combined with the Kohn-Sham equation based on the density functional theory, this method virtually satisfies our requirement. In order to investigate time-dependent phenomena, we apply the time-dependent Kohn-Sham equation. Adopting the finite difference method, we are able to follow the development of quantum many-body system. As an example, we estimate the effects of the potential height, the electric field, and many-body interactions in some transition processes in quantum wells coupled by a tunneling barrier. This example is important in itself in relation to semiconductor superlattices and also serves as a benchmark for quantum simulations, variety of geometry corresponding to that of classical particles.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1994-03-15
28巻
2号
開始ページ 45
終了ページ 52
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002307158
JaLCDOI 10.18926/15450
フルテキストURL Mem_Fac_Eng_OU_22_35.pdf
著者 東辻 浩夫|
抄録 Several methods to derive thermodynamic sum rules for a system including charged particle are proposed and applied to charged mixtures as well as one-component systems. The validity of the statements is examined carefully with respect to the ordering in the powers of the wave number. As for the mixture of electrons and ions, it is shown how the aspect of the one-component plasma or the ionic mixture appears when electrons become strongly degenerate.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1988-03-31
22巻
開始ページ 35
終了ページ 44
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002307661
JaLCDOI 10.18926/15449
フルテキストURL Mem_Fac_Eng_OU_22_15.pdf
著者 古谷 洋一郎| 東辻 浩夫| Komaki Kunitaka| Tanabe Masahiro|
抄録 An effective potential of an isolated partially ionized high-Z ion, calculated within the framework of the statistical models of atoms, is injected into the one-electron Schrödinger equation, in view of evaluating the electron density and comparing it with the results of statistical models. Starting from this initial value, a self-consistent electron density is obtained on the basis of the density functional theory, where quantum natures of electrons are fully taken into account.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1988-03-31
22巻
開始ページ 15
終了ページ 34
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002307361
JaLCDOI 10.18926/15444
フルテキストURL Mem_Fac_Eng_OU_26_2_129.pdf
著者 東辻 浩夫|
抄録 The spectrum of Schottky noise in ion storage rings is analyzed as density fluctuations in effectively one-dimensional plasmas. Strong coupling effects in these plasmas are discussed in relation to experimental observations.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1992-03-28
26巻
2号
開始ページ 129
終了ページ 138
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002307668
JaLCDOI 10.18926/15434
フルテキストURL Mem_Fac_Eng_OU_28_1_27.pdf
著者 東辻 浩夫| Tachibana Hiroyuki| Fujimura Hidenori| 奈良 重俊|
抄録 The ground states of interacting electrons in coupled quantum wires are analyzed on the basis of the density functional theory. The exchange-correlation potential is calculated from 'exact' results given by the Green's function Monte Carlo method in two and three dimensions. It is shown that the critical density signifying the change from symmetrical to asymmetrical ground state is weakly dependent on the details of the exchange-correlation potential. These critical values are compared with the result of the three-dimensional analysis for a single wire.
出版物タイトル Memoirs of the Faculty of Engineering, Okayama University
発行日 1993-11-30
28巻
1号
開始ページ 27
終了ページ 38
ISSN 0475-0071
言語 English
論文のバージョン publisher
NAID 120002307565