JaLCDOI 10.18926/20011
FullText URL Mem_Fac_Eng_OU_29_1_7.pdf
Author Hiroyuki Tachibana| Totsuji, Hiroo| Nara, Shigetoshi| Totsuji, Chieko|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1994-11-30
Volume volume29
Issue issue1
Start Page 7
End Page 14
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002310741
JaLCDOI 10.18926/19674
FullText URL Mem_Fac_Eng_OU_33_2_71.pdf
Author Tsuruta, Kenji| Totsuji, Hiroo| Totsuji, Chieko|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1999-04-27
Volume volume33
Issue issue2
Start Page 71
End Page 77
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309027
JaLCDOI 10.18926/19673
FullText URL Mem_Fac_Eng_OU_33_2_61.pdf
Author Totsuji, Hiroo| Tsuruta, Kenji| Totsuji, Chieko|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1999-04-27
Volume volume33
Issue issue2
Start Page 61
End Page 69
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309106
JaLCDOI 10.18926/19671
FullText URL Mem_Fac_Eng_OU_33_2_51.pdf
Author Totsuji, Hiroo| Tsuruta, Kenji| Totsuji, Chieko|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1999-04-27
Volume volume33
Issue issue2
Start Page 51
End Page 59
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309192
JaLCDOI 10.18926/19636
FullText URL Mem_Fac_Eng_OU_32_23.pdf
Author Totsuji, Hiroo| Kishimoto, Tokunari| Totsuji, Chieko|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1998-04-20
Volume volume32
Issue issue1-2
Start Page 23
End Page 41
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002309150
JaLCDOI 10.18926/17833
FullText URL Mem_Fac_Eng_OU_43_27.pdf
Author Totsuji, Hiroo|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2009-01
Volume volume43
Start Page 27
End Page 31
ISSN 1349-6115
language 英語
File Version publisher
NAID 120002308947
JaLCDOI 10.18926/17831
FullText URL Mem_Fac_Eng_OU_43_22.pdf
Author Totsuji, Hiroo| Chai Hong| Totsuji, Chieko| Tsuruta, Kenji|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2009-01
Volume volume43
Start Page 22
End Page 26
ISSN 1349-6115
language 英語
File Version publisher
NAID 120002308966
JaLCDOI 10.18926/17829
FullText URL Mem_Fac_Eng_OU_43_16.pdf
Author Kurose Tomoyuki| Tsuruta, Kenji| Totsuji, Chieko| Totsuji, Hiroo|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2009-01
Volume volume43
Start Page 16
End Page 21
ISSN 1349-6115
language 英語
File Version publisher
NAID 120002308928
JaLCDOI 10.18926/17826
FullText URL Mem_Fac_Eng_OU_43_8.pdf
Author Umeda Ryosuke| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 2009-01
Volume volume43
Start Page 8
End Page 15
ISSN 1349-6115
language 英語
File Version publisher
NAID 120002308833
JaLCDOI 10.18926/15497
FullText URL Mem_Fac_Eng_OU_24_2_41.pdf
Author Totsuji, Hiroo|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-03-29
Volume volume24
Issue issue2
Start Page 41
End Page 47
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307289
JaLCDOI 10.18926/15490
FullText URL Mem_Fac_Eng_OU_25_1_51.pdf
Author Totsuji, Hiroo|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1990-12-14
Volume volume25
Issue issue1
Start Page 51
End Page 57
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307188
JaLCDOI 10.18926/15482
FullText URL Mem_Fac_Eng_OU_24_1_93.pdf
Author Totsuji, Hiroo| Hatatani, Teruki|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1989-11-29
Volume volume24
Issue issue1
Start Page 93
End Page 105
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307513
JaLCDOI 10.18926/15468
FullText URL Mem_Fac_Eng_OU_23_1_69.pdf
Author Totsuji, Hiroo| Takei Makoto|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1988-11-22
Volume volume23
Issue issue1
Start Page 69
End Page 82
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307988
JaLCDOI 10.18926/15460
FullText URL Mem_Fac_Eng_OU_28_2_45.pdf
Author Totsuji, Hiroo| Hashimoto, Seiji| Nara, Shigetoshi|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1994-03-15
Volume volume28
Issue issue2
Start Page 45
End Page 52
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307158
JaLCDOI 10.18926/15450
FullText URL Mem_Fac_Eng_OU_22_35.pdf
Author Totsuji, Hiroo|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1988-03-31
Volume volume22
Start Page 35
End Page 44
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307661
JaLCDOI 10.18926/15449
FullText URL Mem_Fac_Eng_OU_22_15.pdf
Author Furutani, Yoichiro| Totsuji, Hiroo| Komaki Kunitaka| Tanabe Masahiro|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1988-03-31
Volume volume22
Start Page 15
End Page 34
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307361
JaLCDOI 10.18926/15444
FullText URL Mem_Fac_Eng_OU_26_2_129.pdf
Author Totsuji, Hiroo|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1992-03-28
Volume volume26
Issue issue2
Start Page 129
End Page 138
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307668
JaLCDOI 10.18926/15434
FullText URL Mem_Fac_Eng_OU_28_1_27.pdf
Author Totsuji, Hiroo| Tachibana Hiroyuki| Fujimura Hidenori| Nara, Shigetoshi|
Abstract 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.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1993-11-30
Volume volume28
Issue issue1
Start Page 27
End Page 38
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307565
JaLCDOI 10.18926/15432
FullText URL Mem_Fac_Eng_OU_28_1_1.pdf
Author Nara, Shigetoshi| Miho Shigeru| Totsuji, Hiroo|
Abstract The structural stabilities of bulk Si, Ge, and GaAs are discussed based on the total energy evaluated by the summation of the band structure energy and the short-range repulsive potential between ions. The band structure energy is calculated by means of the simple tight-binding method. The tight-binding parameters are determined so as to fit to the results of a pseude potential calculation and Harrison's model is employed to include the influence of lattice deformation. The short-range-force is assumed to be of the exponential form and parameters are determined so as to reproduce an experimental value of bulk modulus. This treatment qualitatively well describes structural properties in spite of the simple computational procedure and roughly gives the known variation of the total energy for a <100> uniaxial strain. This method is able to be applied to an investigation of the structural stabilities of superlattices, for example, a strained layer superlattice consisting of hetero-semiconductors.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1993-11-30
Volume volume28
Issue issue1
Start Page 1
End Page 25
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307238
JaLCDOI 10.18926/15422
FullText URL Mem_Fac_Eng_OU_29_2_57.pdf
Author Totsuji, Hiroo|
Abstract As plasmas with extremely reduced dimensionality, properties of one-dimensional classical plasmas are analyzed in the domain of strong coupling and static and dynamic structure factors and the plasmon dispersion relation are obtained. These plasmas may be realized in Penning traps with sufficiently strong confinement and also in semiconductor quantum wires under appropriate conditions.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1995-03-27
Volume volume29
Issue issue2
Start Page 57
End Page 65
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307838