JaLCDOI | 10.18926/19671 |
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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 | English |
File Version | publisher |
NAID | 120002309192 |
JaLCDOI | 10.18926/19674 |
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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 | English |
File Version | publisher |
NAID | 120002309027 |
JaLCDOI | 10.18926/19673 |
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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 | English |
File Version | publisher |
NAID | 120002309106 |
JaLCDOI | 10.18926/15361 |
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FullText URL | Mem_Fac_Eng_OU_35_77.pdf |
Author | Kishimoto Tokunari| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | In order to perform the large-scale molecular dynamics simulation of the Yukawa system, a mathematical expression for molecular dynamics using the fast multipole method is described. The model simulations are also performed to test the performance of our implementation of the FMM. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2001-03-27 |
Volume | volume35 |
Issue | issue1-2 |
Start Page | 77 |
End Page | 95 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 120002307940 |
JaLCDOI | 10.18926/15358 |
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FullText URL | Mem_Fac_Eng_OU_35_63.pdf |
Author | Shinomiya Shigeru| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | We present a theoretical study of Si(1-x)Ge(x) alloys based on tight-binding molecular dynamics (TBMD) calculations. First, we introduce a new set of nonorthogonal tight-binding parameters for silicon and germanium based on the previous work by Menon and Subbaswamy [Phys. Rev. B 55, 9231 (1997); J. Phys: Condens. Matter 10, 10991 (1998)]. We then apply the method to structural analyses of Si(1-x)Ge(x) alloys. The equilibrium volume and atomic structure for a given x are obtained by the TBMD method. We also calculate the bulk modulus B, elastic constants C(11), C(12) and C(44) as a function of x. The results show that the moduli vary monotonically, but nonlinearly, between the values of Si crystal and Ge crystal. The validity of the results is also discussed. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2001-03-27 |
Volume | volume35 |
Issue | issue1-2 |
Start Page | 63 |
End Page | 75 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 120002307673 |
JaLCDOI | 10.18926/46999 |
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FullText URL | mfe_36_1_041_049.pdf |
Author | Totsuji, Hiroo| Kishimoto, Tokunari| Totsuji, Chieko| Tsuruta, Kenji| |
Abstract | The ground state of spherical clusters of charged particles of one species confined by the three-dimensional parabolic potential is investigated by molecular dynamics simulations with the system size from N = 5000 to N = 1.2 × 10(5) . The cohesive energy per particle is compared between the shell-structured clusters and spherical finite bcc lattices with relaxed surfaces, the former and the latter being the ground states for small systems and for the large enough systems, respectively. It is shown that, when N > N(c)(N(c) > N), finite bcc lattices with relaxed surfaces (the shell structures) have stronger cohesion than the shell structures (finite bcc lattices with relaxed surfaces) and the critical value of the transition N(c) is estimated to be 10(4) < N(c) < 1.4 × 10(4) . The nucleation of the bcc lattice in the shell-structured cluster of 2 × 10(4) ions is observed. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2001-12 |
Volume | volume36 |
Issue | issue1 |
Start Page | 41 |
End Page | 49 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 80015112663 |
JaLCDOI | 10.18926/46968 |
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FullText URL | mfe_37_1_011_014.pdf |
Author | Totsuji, Chieko| Limant, Muhammad S.| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | A theoretical approach which has been successful in reproducing results of molecular-dynamics simulations on dusty plasmas is applied to estimate the screening length and the electric charge of two-dimensional dust crystals of melamine particles in the discharge chamber experiment. It has been found that the screening length is of the same order of magnitude as the inter-particle distance and the electric charge decreases on increasing number density of dust particles. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2002-11 |
Volume | volume37 |
Issue | issue1 |
Start Page | 11 |
End Page | 14 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 80015784816 |
JaLCDOI | 10.18926/46949 |
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FullText URL | mfe_38_1-2_029_032.pdf |
Author | Totsuji, Hiroo| Totsuji, Chieko| Ogawa, Takafumi| Tsuruta, Kenji| |
Abstract | The structure of dust particles in dusty plasmas under microgravity has been analyzed by molecular dynamics simulation. The charge neutrality condition satisfied by the system composed of dust particles and ambient plasma is properly taken into account. It is shown that dust particles form shell structures at low temperatures and the number of shells are obtained as a phase diagram in the plane of two parameters characterizing the system: the number of particles and the strength of screening. It is also shown that these structures are almost independent of the strength of screening. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2004-03 |
Volume | volume38 |
Issue | issue1-2 |
Start Page | 29 |
End Page | 32 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 80016863328 |
JaLCDOI | 10.18926/46950 |
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FullText URL | mfe_38_1-2_033_037.pdf |
Author | Liman, M. Sanusi| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | The dynamic structure factor and the spectrum of the momentum-density fluctuations of 2D Yukawa liquids are analyzed in the domain of weak and intermediate coupling and screenlng parameters. The dispersion relations of the longitudinal and transverse collective excitations are obtained and compared with the random phase approximation (RPA) and harmonic approximation for triangular lattice. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2004-03 |
Volume | volume38 |
Issue | issue1-2 |
Start Page | 33 |
End Page | 37 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 80016863329 |
Author | Totsuji, Hiroo| Liman, M. Sanusi| Totsuji, Chieko| Tsuruta, Kenji| |
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Published Date | 2004-7 |
Publication Title | Physical Review E |
Volume | volume70 |
Issue | issue1 |
Content Type | Journal Article |
JaLCDOI | 10.18926/14152 |
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FullText URL | Mem_Fac_Eng_39_1_52.pdf |
Author | Kanamori, Katsuya| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | Thermal behavior of Coulomb clusters in a three dimensional confining potential is investigated by molecular dynamics simulations for system sizes of 1,000 to 20,288 ions. The specific heat of the system of shell-structured 20,000 ions is peaked almost at the same temperature as the system of bcc-structured 20,288 ions with much sharper structure for the latter. The diffusion coefficient and the peak to valley ratio of the two-dimensional pair distribution function on the outermost shell are obtained both as a function of temperature. The rotational movement of each shell in the system of 104 ions is observed. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2005-01 |
Volume | volume39 |
Issue | issue1 |
Start Page | 52 |
End Page | 55 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 120002308445 |
JaLCDOI | 10.18926/14150 |
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FullText URL | Mem_Fac_Eng_39_1_46.pdf |
Author | Kadono, Keisuke| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | We present a real-space, polynomial-expansion approach to electron dynamics in nanostructured semiconductors. The Chebyshev expansion method is employed for efficient calculation of timeevolution of single-electron wave function. Details of the formulation are described. The method is applied to the electron transport in nanostructured semiconductors such as Si nanowires. The mean-square displacement and diffusivity of electron in Si chains are obtained as functions of length of the chains. The results show clearly ballistic behavior of electron in the pure Si chain. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2005-01 |
Volume | volume39 |
Issue | issue1 |
Start Page | 46 |
End Page | 51 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 120002308231 |
Author | Totsuji, Hiroo| Totsuji, Chieko| Ogawa, Takafumi| Tsuruta, Kenji| |
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Published Date | 2005-4 |
Publication Title | Physical Review E |
Volume | volume71 |
Issue | issue4 |
Content Type | Journal Article |
Author | Totsuji, Hiroo| Ogawa, Takafumi| Totsuji, Chieko| Tsuruta, Kenji| |
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Published Date | 2005-9 |
Publication Title | Physical Review E |
Volume | volume72 |
Issue | issue3 |
Content Type | Journal Article |
JaLCDOI | 10.18926/14120 |
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FullText URL | Mem_Fac_Eng_OU_40_1_36.pdf |
Author | Uchida, Atsushi| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | We present a Stochastic-Difference-Equation (SDE) approach to long time-scale molecular dynamics (MD) simulations, which are required for nanosecond-scale phenomena. In this method, the MD trajectory in a fixed time period is obtained as a stationary solution of an action functional based on an error accumulation of the equation of motion along the path, thus reducing the problem to a boundary-value problem, instead of an initial-value problem in the ordinary MD method. We apply the method to formation processes of Cu thin film via nanocluster deposition onto a substrate. The applicability of the SDE algorithm to the problem and the effects of the choice of SDE parameters on the optimization processes of configuration pathway are examined. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2006-01 |
Volume | volume40 |
Issue | issue1 |
Start Page | 36 |
End Page | 39 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 120002308517 |
JaLCDOI | 10.18926/14121 |
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FullText URL | Mem_Fac_Eng_OU_40_1_40.pdf |
Author | Takashi, Miyake| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | The electron system of arbitrary degeneracy can be mapped onto a classical system where electrons of the same spin are assigned an additional interaction and the effect of degeneracy is taken into account through an imaginative temperature. We apply this method to electrons in quantum dots modeled as two-dimensional electron liquid confined in a finite domain by a harmonic potential. We analyze distribution functions by molecular dynamics instead of solving integral equations which are not so useful in the case without translational invariance. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2006-01 |
Volume | volume40 |
Issue | issue1 |
Start Page | 40 |
End Page | 43 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 120002308268 |
JaLCDOI | 10.18926/14119 |
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FullText URL | Mem_Fac_Eng_OU_40_1_31.pdf |
Author | Ogawa, Takafumi| Totsuji, Chieko| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | We analyze the melting of spherical Yukawa clusters by Monte Carlo simulations. Spherical clusters are expected to be found in dusty plasmas in an isotropic environment such as microgravity and serve as a model for classical clusters. We obtain the specific heat through fluctuations of the potential energy and identify its peak as the transition temperature. Melting temperatures are compared with those of bulk Yukawa systems and it is confirmed that the melting temperature increases and approaches the bulk value with the increase of the system size. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2006-01 |
Volume | volume40 |
Issue | issue1 |
Start Page | 31 |
End Page | 35 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 120002308329 |
JaLCDOI | 10.18926/14058 |
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FullText URL | Mem_Fac_Eng_OU_42_44.pdf |
Author | Ogawa Takafumi| Tsuruta, Kenji| Totsuji, Chieko| Totsuji, Hiroo| Hiroshi Iyetomi| |
Abstract | To analyze vibrational properties of Si crystal with a single charge-neutral vacancy, we perform large-scale simulations based on tight-binding molecular-dynamics method. Vibrational modes and frequencies are obtained by diagonalizing dynamical matrix within a harmonic approximation. Results indicate that there exist vibrational modes spatially localized around the vacancy and large frequency shifts associated with the localized modes contribute significantly to reduction of the vibrational free energy. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2008-01 |
Volume | volume42 |
Issue | issue1 |
Start Page | 44 |
End Page | 47 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 120002308412 |
JaLCDOI | 10.18926/14061 |
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FullText URL | Mem_Fac_Eng_OU_42_56.pdf |
Author | Miyake Takashi| Totsuji, Chieko| Nakanishi Kenta| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | We analyze the ground state of the two-dimensional quantum system of electrons confined in a parabolic potential with the system size around 100. We map the system onto a classical system on the basis of the classical-map hypernetted-chain (CHNC) method which has been proven to work in the integral-equation-based analyses of uniform unbounded systems and then apply classical numerical simulations. We find that the confined system undergoes the transition to the spin polarized state with the decrease of the average density and the corresponding critical value is as low as rs ∼ 0.3 in terms of the usual rs parameter estimated for the average density. As the ground state for given value of the rs parameter, our data give the critical value for the transition around 20 which is consistent with the known possibility. The advantage of our method is a direct applicability to geometrically complex systems which are difficult to analyze by integral equations. The application to the structure like quantum dots reported here is the first example of such applications. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2008-01 |
Volume | volume42 |
Issue | issue1 |
Start Page | 56 |
End Page | 59 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 120002308633 |
JaLCDOI | 10.18926/14059 |
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FullText URL | Mem_Fac_Eng_OU_42_48.pdf |
Author | Totsuji, Chieko| Miyake Takashi| Nakanishi Kenta| Tsuruta, Kenji| Totsuji, Hiroo| |
Abstract | Based on the mapping introduced by the classical-map hypernetted-chain (CHNC) method, classical numerical simulations, Monte Carlo and molecular dynamics, have been applied to the twodimensional electron fluid and the results are compared with those of quantum Monte Carlo simulations hitherto reported. It is shown that polarization properties of the ground state obtained by the diffusion Monte Carlo method are reproduced within the accuracy of quantum simulations by both of two mapping functions for the quantum temperature which have been proposed within the CHNC method. These results may serve as the basis of numerical simulations based on the CHNC method which are applicable to finite non-periodic systems like quantum dots and systems at finite temperatures. |
Publication Title | Memoirs of the Faculty of Engineering, Okayama University |
Published Date | 2008-01 |
Volume | volume42 |
Issue | issue1 |
Start Page | 48 |
End Page | 52 |
ISSN | 0475-0071 |
language | English |
File Version | publisher |
NAID | 120002308425 |