| JaLCDOI | 10.18926/14059 |
|---|---|
| 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 |
| JaLCDOI | 10.18926/14061 |
|---|---|
| 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 | 10.18926/14119 |
|---|---|
| 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 | 10.18926/14120 |
|---|---|
| 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 |
|---|---|
| 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 | 10.18926/14150 |
|---|---|
| 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 |
| JaLCDOI | 10.18926/14152 |
|---|---|
| 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 | 10.18926/15358 |
|---|---|
| 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 | 10.18926/15361 |
|---|---|
| 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 |
| FullText URL | fulltext.pdf |
|---|---|
| Author | Machida, Narumi| Misawa, Masaaki| Kezuka, Yuki| Tsuruta, Kenji| |
| Keywords | Calcite Stearic acid Surface adsorption Density functional calculation Molecular dynamics |
| Published Date | 2022-08-06 |
| Publication Title | e-Journal of Surface Science and Nanotechnology |
| Volume | volume20 |
| Issue | issue4 |
| Publisher | The Japan Society of Vacuum and Surface Science |
| Start Page | 261 |
| End Page | 265 |
| ISSN | 1348-0391 |
| Content Type | Journal Article |
| language | English |
| OAI-PMH Set | 岡山大学 |
| Copyright Holders | ©2022 The author(s) |
| File Version | publisher |
| DOI | 10.1380/ejssnt.2022-041 |
| Web of Science KeyUT | 000891603200001 |
| Related Url | isVersionOf https://doi.org/10.1380/ejssnt.2022-041 |
| 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 | English |
| File Version | publisher |
| NAID | 120002308833 |
| 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 | English |
| File Version | publisher |
| NAID | 120002308928 |
| 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 | English |
| File Version | publisher |
| NAID | 120002308966 |
