start-ver=1.4 cd-journal=joma no-vol=33 cd-vols= no-issue=2 article-no= start-page=51 end-page=59 dt-received= dt-revised= dt-accepted= dt-pub-year=1999 dt-pub=19990427 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Density Functional Molecular Dynamics of Hydrogen Plasma en-subtitle= kn-subtitle= en-abstract= kn-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 ƒม(s), we have increasingly strong screening of proton charge by electrons and the decrease of electron density in the domain between protons. en-copyright= kn-copyright= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=1 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=2 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=Department of Electrical and Electronic Engineering affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering END start-ver=1.4 cd-journal=joma no-vol=33 cd-vols= no-issue=2 article-no= start-page=71 end-page=77 dt-received= dt-revised= dt-accepted= dt-pub-year=1999 dt-pub=19990427 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=O(N) Tight-Binding Algorithm for Large-Scale Molecular Dynamics Simulations en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=1 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=2 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=Department of Electrical and Electronic Engineering affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering END start-ver=1.4 cd-journal=joma no-vol=33 cd-vols= no-issue=2 article-no= start-page=61 end-page=69 dt-received= dt-revised= dt-accepted= dt-pub-year=1999 dt-pub=19990427 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Multicomponent Plasmas in Penning-Malmberg Traps en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=1 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=2 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=Department of Electrical and Electronic Engineering affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering END start-ver=1.4 cd-journal=joma no-vol=35 cd-vols= no-issue=1-2 article-no= start-page=77 end-page=95 dt-received= dt-revised= dt-accepted= dt-pub-year=2001 dt-pub=20010327 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Molecular Dynamics of Yukawa System using the Fast Multipole Method en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=KishimotoTokunari kn-aut-sei=Kishimoto kn-aut-mei=Tokunari aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering affil-num=4 en-affil= kn-affil=Department of Electrical and Electronic Engineering END start-ver=1.4 cd-journal=joma no-vol=35 cd-vols= no-issue=1-2 article-no= start-page=63 end-page=75 dt-received= dt-revised= dt-accepted= dt-pub-year=2001 dt-pub=20010327 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Nonorthogonal Tight-Binding Molecular Dynamics for Si(1-x)Ge(x) Alloys en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=ShinomiyaShigeru kn-aut-sei=Shinomiya kn-aut-mei=Shigeru aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering affil-num=4 en-affil= kn-affil=Department of Electrical and Electronic Engineering END start-ver=1.4 cd-journal=joma no-vol=36 cd-vols= no-issue=1 article-no= start-page=41 end-page=49 dt-received= dt-revised= dt-accepted= dt-pub-year=2001 dt-pub=200112 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Structure and Cohesive Energy of Large Spherical Coulomb Clusters en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KishimotoTokunari en-aut-sei=Kishimoto en-aut-mei=Tokunari kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Okayama University affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Okayama University affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Okayama University affil-num=4 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Okayama University END start-ver=1.4 cd-journal=joma no-vol=37 cd-vols= no-issue=1 article-no= start-page=11 end-page=14 dt-received= dt-revised= dt-accepted= dt-pub-year=2002 dt-pub=200211 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Estimation of the screening length and the electric charge on particles in single-layered dusty plasma crystals en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=LimantMuhammad S. en-aut-sei=Limant en-aut-mei=Muhammad S. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Department of Electrical and Electronic Engineering Faculty of Engineering, Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering Faculty of Engineering, Okayama University affil-num=4 en-affil= kn-affil=Department of Electrical and Electronic Engineering Faculty of Engineering, Okayama University END start-ver=1.4 cd-journal=joma no-vol=38 cd-vols= no-issue=1-2 article-no= start-page=29 end-page=32 dt-received= dt-revised= dt-accepted= dt-pub-year=2004 dt-pub=200403 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Structure of Dusty Plasma under Microgravity en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OgawaTakafumi en-aut-sei=Ogawa en-aut-mei=Takafumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Okayama University affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Okayama University affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Okayama University affil-num=4 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Okayama University END start-ver=1.4 cd-journal=joma no-vol=38 cd-vols= no-issue=1-2 article-no= start-page=33 end-page=37 dt-received= dt-revised= dt-accepted= dt-pub-year=2004 dt-pub=200403 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Dynamical Properties of Two-Dimensional Yukawa Liquids: A Molecular Dynamics Study en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=LimanM. Sanusi en-aut-sei=Liman en-aut-mei=M. Sanusi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Facu.lty of Engineering, Okayama University affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Facu.lty of Engineering, Okayama University affil-num=4 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Facu.lty of Engineering, Okayama University END start-ver=1.4 cd-journal=joma no-vol=70 cd-vols= no-issue=1 article-no= start-page= end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2004 dt-pub=20047 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Thermodynamics of a two-dimensional Yukawa fluid en-subtitle= kn-subtitle= en-abstract= kn-abstract=

Thermodynamic quantities of a two-dimensional Yukawa system, a model for various systems including single-layered dust particles observed in dusty plasmas, are obtained and expressed by simple interpolation formulas. In the domain of weak coupling, the analytical method based on the cluster expansion is applied and, in the domain of intermediate and strong coupling, numerical simulations are performed. Due to reduced dimensionality, the treatment based on the mean field fails at the short range and exact behavior of the binary correlation is to be taken into account even in the case of weak coupling.

en-copyright= kn-copyright= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=LimanM. Sanusi en-aut-sei=Liman en-aut-mei=M. Sanusi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Okayama University affil-num=2 en-affil= kn-affil=Okayama University affil-num=3 en-affil= kn-affil=Okayama University affil-num=4 en-affil= kn-affil=Okayama University en-keyword=dusty plasma kn-keyword=dusty plasma en-keyword=cluster expansion kn-keyword=cluster expansion en-keyword=electron liquids kn-keyword=electron liquids END start-ver=1.4 cd-journal=joma no-vol=39 cd-vols= no-issue=1 article-no= start-page=52 end-page=55 dt-received= dt-revised= dt-accepted= dt-pub-year=2005 dt-pub=200501 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Large-Scale Molecular Dynamics Simulation of CoulombClusters: A Finite-Temperature Analysis en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=KanamoriKatsuya en-aut-sei=Kanamori en-aut-mei=Katsuya kn-aut-name=‹เXŽ–็ kn-aut-sei=‹เX kn-aut-mei=Ž–็ aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Faculty of Engineering, Okayama University affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Faculty of Engineering, Okayama University affil-num=4 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Faculty of Engineering, Okayama University END start-ver=1.4 cd-journal=joma no-vol=39 cd-vols= no-issue=1 article-no= start-page=46 end-page=51 dt-received= dt-revised= dt-accepted= dt-pub-year=2005 dt-pub=200501 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Electron Dynamics in Semiconducting Nanowires: A Real-Space,Polynomial-Expansion Approach en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=KadonoKeisuke en-aut-sei=Kadono en-aut-mei=Keisuke kn-aut-name=–ๅ–์Œb“T kn-aut-sei=–ๅ–์ kn-aut-mei=Œb“T aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Faculty of Engineering, Okayama University affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Faculty of Engineering, Okayama University affil-num=4 en-affil= kn-affil=Department of Electrical and Electronic Engineering, Faculty of Engineering, Okayama University END start-ver=1.4 cd-journal=joma no-vol=71 cd-vols= no-issue=4 article-no= start-page= end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2005 dt-pub=20054 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Ordering of dust particles in dusty plasmas under microgravity en-subtitle= kn-subtitle= en-abstract= kn-abstract=

Structure formation of dust particles in dusty plasmas under microgravity has been simulated by the molecular dynamics method. It is shown that, at low temperatures, dust particles are organized into layered spherical shells. The number of shells is a function of the system size and the strength of screening by ambient plasma particles, while the dependency on the latter is much weaker. In the simulation, the condition of the charge neutrality satisfied by the system of dust particles and plasma particles is properly taken into account.

en-copyright= kn-copyright= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OgawaTakafumi en-aut-sei=Ogawa en-aut-mei=Takafumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Okayama University affil-num=2 en-affil= kn-affil=Okayama University affil-num=3 en-affil= kn-affil=Okayama University affil-num=4 en-affil= kn-affil=Okayama University en-keyword=coupled yukawa systems kn-keyword=coupled yukawa systems en-keyword=coulomb kn-keyword=coulomb en-keyword=crystals kn-keyword=crystals en-keyword=thermodynamics kn-keyword=thermodynamics en-keyword=dynamics kn-keyword=dynamics en-keyword=energy kn-keyword=energy en-keyword=limit kn-keyword=limit END start-ver=1.4 cd-journal=joma no-vol=72 cd-vols= no-issue=3 article-no= start-page= end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2005 dt-pub=20059 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Structure of spherical Yukawa clusters: A model for dust particles in dusty plasmas in an isotropic environment en-subtitle= kn-subtitle= en-abstract= kn-abstract=

The structure of spherical clusters composed of Yukawa particles is analyzed by molecular dynamics simulations and theoretical approaches as a model for dust particles in dusty plasmas in the isotropic environment. The latter condition is expected to be realized under microgravity or by active cancellation of the effect of gravity on the ground. It is found that, at low temperatures, Yukawa particles form spherical shells and, when scaled by the mean distance, the structure is almost independent of the strength of screening including the case of the Coulomb interaction. The positions and populations of shells and the conditions for the change of the number of shells are expressed by simple interpolation formulas. Shells have an approximately equal spacing close to that of triangular lattice planes in the bulk close-packed structures. It is shown that, when the cohesive energy in each shell is properly taken into account, the shell model reproduces the structure of spherical Yukawa clusters to a good accuracy.

en-copyright= kn-copyright= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=OgawaTakafumi en-aut-sei=Ogawa en-aut-mei=Takafumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Okayama University affil-num=2 en-affil= kn-affil=Okayama University affil-num=3 en-affil= kn-affil=Okayama University affil-num=4 en-affil= kn-affil=Okayama University en-keyword=coulomb crystals kn-keyword=coulomb crystals en-keyword=simulation kn-keyword=simulation en-keyword=energy kn-keyword=energy en-keyword=charge kn-keyword=charge END start-ver=1.4 cd-journal=joma no-vol=40 cd-vols= no-issue=1 article-no= start-page=36 end-page=39 dt-received= dt-revised= dt-accepted= dt-pub-year=2006 dt-pub=200601 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Stochastic-Dierence-Equation Method for Long Time-scaleMolecular Dynamics Simulations en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=UchidaAtsushi en-aut-sei=Uchida en-aut-mei=Atsushi kn-aut-name=“เ“cŒ๚ kn-aut-sei=“เ“c kn-aut-mei=Œ๚ aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University affil-num=4 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University END start-ver=1.4 cd-journal=joma no-vol=40 cd-vols= no-issue=1 article-no= start-page=40 end-page=43 dt-received= dt-revised= dt-accepted= dt-pub-year=2006 dt-pub=200601 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Distribution of Electrons in Quantum Dots Analyzed by Classical Mapping and Molecular Dynamics en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=TakashiMiyake en-aut-sei=Takashi en-aut-mei=Miyake kn-aut-name=ŽO‘๎—ฒ kn-aut-sei=ŽO‘๎ kn-aut-mei=—ฒ aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Division of Industrial Innovation Sciences, Graduate School of Natural Science and Technology, Okayama University affil-num=2 en-affil= kn-affil=Division of Industrial Innovation Sciences, Graduate School of Natural Science and Technology, Okayama University affil-num=3 en-affil= kn-affil=Division of Industrial Innovation Sciences, Graduate School of Natural Science and Technology, Okayama University affil-num=4 en-affil= kn-affil=Division of Industrial Innovation Sciences, Graduate School of Natural Science and Technology, Okayama University END start-ver=1.4 cd-journal=joma no-vol=40 cd-vols= no-issue=1 article-no= start-page=31 end-page=35 dt-received= dt-revised= dt-accepted= dt-pub-year=2006 dt-pub=200601 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Melting of Spherical Yukawa Clusters Analyzed by Monte CarloSimulation en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=OgawaTakafumi en-aut-sei=Ogawa en-aut-mei=Takafumi kn-aut-name=ฌ์‹MŽj kn-aut-sei=ฌ์ kn-aut-mei=‹MŽj aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Division of Industrial Innovation Sciences, Graduate School of Natural Science and Technology, Okayama University affil-num=2 en-affil= kn-affil=Division of Industrial Innovation Sciences, Graduate School of Natural Science and Technology, Okayama University affil-num=3 en-affil= kn-affil=Division of Industrial Innovation Sciences, Graduate School of Natural Science and Technology, Okayama University affil-num=4 en-affil= kn-affil=Division of Industrial Innovation Sciences, Graduate School of Natural Science and Technology, Okayama University END start-ver=1.4 cd-journal=joma no-vol=42 cd-vols= no-issue=1 article-no= start-page=44 end-page=47 dt-received= dt-revised= dt-accepted= dt-pub-year=2008 dt-pub=200801 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Vibrational Properties of Si Crystal with Vacancy : A Tight-Binding Study en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=OgawaTakafumi kn-aut-sei=Ogawa kn-aut-mei=Takafumi aut-affil-num=1 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=2 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=4 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=HiroshiIyetomi kn-aut-sei=Hiroshi kn-aut-mei=Iyetomi aut-affil-num=5 ORCID= affil-num=1 en-affil= kn-affil=Department of Electrical and Electronic Engineering Okayama University affil-num=2 en-affil= kn-affil=Department of Electrical and Electronic Engineering Okayama University affil-num=3 en-affil= kn-affil=Department of Electrical and Electronic Engineering Okayama University affil-num=4 en-affil= kn-affil=Department of Electrical and Electronic Engineering Okayama University affil-num=5 en-affil= kn-affil=Department of Physics Niigata University END start-ver=1.4 cd-journal=joma no-vol=42 cd-vols= no-issue=1 article-no= start-page=56 end-page=59 dt-received= dt-revised= dt-accepted= dt-pub-year=2008 dt-pub=200801 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Spin Polarization of Two-Dimensional Electron System in a Finite Domain en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=MiyakeTakashi kn-aut-sei=Miyake kn-aut-mei=Takashi aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=2 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=NakanishiKenta kn-aut-sei=Nakanishi kn-aut-mei=Kenta aut-affil-num=3 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=4 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=5 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University affil-num=4 en-affil= kn-affil=Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University affil-num=5 en-affil= kn-affil=Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University END start-ver=1.4 cd-journal=joma no-vol=42 cd-vols= no-issue=1 article-no= start-page=48 end-page=52 dt-received= dt-revised= dt-accepted= dt-pub-year=2008 dt-pub=200801 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Numerical Simulations of Two-dimensional Electron Fluid : An Application of Classical-map Hypernetted-chain Method en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=1 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=MiyakeTakashi kn-aut-sei=Miyake kn-aut-mei=Takashi aut-affil-num=2 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=NakanishiKenta kn-aut-sei=Nakanishi kn-aut-mei=Kenta aut-affil-num=3 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=4 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=5 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University affil-num=4 en-affil= kn-affil=Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University affil-num=5 en-affil= kn-affil=Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University END start-ver=1.4 cd-journal=joma no-vol=43 cd-vols= no-issue= article-no= start-page=22 end-page=26 dt-received= dt-revised= dt-accepted= dt-pub-year=2009 dt-pub=200901 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Information Transfer and Entanglement Creation by Spin Chains: Effects of Noise and Asymmetry en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=1 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=ChaiHong kn-aut-sei=Chai kn-aut-mei=Hong aut-affil-num=2 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=3 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University affil-num=4 en-affil= kn-affil=Graduate School of Natural Science and Technology, Okayama University END start-ver=1.4 cd-journal=joma no-vol=43 cd-vols= no-issue= article-no= start-page=8 end-page=15 dt-received= dt-revised= dt-accepted= dt-pub-year=2009 dt-pub=200901 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Dispersion Models and Electromagnetic FDTD Analyses ofNanostructured Metamaterials using Parallel Computer en-subtitle= kn-subtitle= en-abstract= kn-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. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=UmedaRyosuke kn-aut-sei=Umeda kn-aut-mei=Ryosuke aut-affil-num=1 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=4 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University END start-ver=1.4 cd-journal=joma no-vol=43 cd-vols= no-issue= article-no= start-page=16 end-page=21 dt-received= dt-revised= dt-accepted= dt-pub-year=2009 dt-pub=200901 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=FDTD Simulations of Acoustic Waves in Two-DimensionalPhononic Crystals using Parallel Computer en-subtitle= kn-subtitle= en-abstract= kn-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glens effecthwith the slab appears due to the negative refractions. The relationship between the focal intensity in the lens effect and the band structure is discussed. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=KuroseTomoyuki kn-aut-sei=Kurose kn-aut-mei=Tomoyuki aut-affil-num=1 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=2 ORCID= en-aut-name=TotsujiChieko en-aut-sei=Totsuji en-aut-mei=Chieko kn-aut-name=“Œ’า็Ž}Žq kn-aut-sei=“Œ’า kn-aut-mei=็Ž}Žq aut-affil-num=3 ORCID= en-aut-name=TotsujiHiroo en-aut-sei=Totsuji en-aut-mei=Hiroo kn-aut-name=“Œ’า_•v kn-aut-sei=“Œ’า kn-aut-mei=_•v aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=4 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University END start-ver=1.4 cd-journal=joma no-vol=44 cd-vols= no-issue= article-no= start-page=7 end-page=12 dt-received= dt-revised= dt-accepted= dt-pub-year=2010 dt-pub=201001 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Numerical Simulation of Acoustic Waves in a Two-Dimensional Phononic Crystal: Negative Refraction en-subtitle= kn-subtitle= en-abstract= kn-abstract=The lens effect of acoustic waves in a two-dimensional (2D) phononic crystal is studied by numerical simulation based on the finite-difference time-domain (FDTD) method. We calculate the phonon band structure of 2D phononic crystals, consisting of metal cylinders placed periodically in water. Lens effect is observed by the negative refraction of acoustic waves, which results in refocusing of the waves at the point outside the crystal. To increase the focal intensity, we introduce a 2D phononic crystal shield with a different composition of material, which returns the incident waves back to the lens via the perfect reflection. Also, the dependence on filling fraction of metal in the crystal is studied. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=MaetaniNoriaki kn-aut-sei=Maetani kn-aut-mei=Noriaki aut-affil-num=1 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=KuroseTomoyuki kn-aut-sei=Kurose kn-aut-mei=Tomoyuki aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University END start-ver=1.4 cd-journal=joma no-vol=44 cd-vols= no-issue= article-no= start-page=1 end-page=6 dt-received= dt-revised= dt-accepted= dt-pub-year=2010 dt-pub=201001 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=FDTD Analysis on Optical Connement Structurewith Electromagnetic Metamaterial en-subtitle= kn-subtitle= en-abstract= kn-abstract=In this paper, we investigate a light-confinement phenomenon in the structure which has triangular latice composed of Double NeGative Metamaterial (DNGM). In geometrical optics consideration, this structure is expected to confine lights completely by sequential refractions in the structure. We demonstrate it by using the two dimensional finite-difference time-domain simulations. We introduce Drude-Lorentz model for dielectric and magnetic dispersion of the material at optical frequencies. We analyze quantitatively the effects of energy loss in the DNGM on the light-confinement efficiency. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=NagaiShinji kn-aut-sei=Nagai kn-aut-mei=Shinji aut-affil-num=1 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=UmedaRyosuke kn-aut-sei=Umeda kn-aut-mei=Ryosuke aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=’฿“cŒ’“๑ kn-aut-sei=’฿“c kn-aut-mei=Œ’“๑ aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=2 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University affil-num=3 en-affil= kn-affil=Graduate School of Natural Science and Technology Okayama University END start-ver=1.4 cd-journal=joma no-vol=10 cd-vols= no-issue= article-no= start-page=4159 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20190913 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Ultrafast isomerization-induced cooperative motions to higher molecular orientation in smectic liquid-crystalline azobenzene molecules en-subtitle= kn-subtitle= en-abstract= kn-abstract=The photoisomerization of molecules is widely used to control the structure of soft matter in both natural and synthetic systems. However, the structural dynamics of the molecules during isomerization and their subsequent response are difficult to elucidate due to their complex and ultrafast nature. Herein, we describe the ultrafast formation of higherorientation of liquid-crystalline (LC) azobenzene molecules via linearly polarized ultraviolet light (UV) using ultrafast time-resolved electron diffraction. The ultrafast orientation is caused by the trans-to-cis isomerization of the azobenzene molecules. Our observations are consistent with simplified molecular dynamics calculations that revealed that the molecules are aligned with the laser polarization axis by their cooperative motion after photoisomerization. This insight advances the fundamental chemistry of photoresponsive molecules in soft matter as well as their ultrafast photomechanical applications. en-copyright= kn-copyright= en-aut-name=HadaMasaki en-aut-sei=Hada en-aut-mei=Masaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=YamaguchiDaisuke en-aut-sei=Yamaguchi en-aut-mei=Daisuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=IshikawaTadahiko en-aut-sei=Ishikawa en-aut-mei=Tadahiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SawaTakayoshi en-aut-sei=Sawa en-aut-mei=Takayoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=IshikawaKen en-aut-sei=Ishikawa en-aut-mei=Ken kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=KoshiharaShin-Ya en-aut-sei=Koshihara en-aut-mei=Shin-Ya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=HayashiYasuhiko en-aut-sei=Hayashi en-aut-mei=Yasuhiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=KatoTakashi en-aut-sei=Kato en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Department of Chemistry & Biotechnology, School of Engineering, The University of Tokyo kn-affil= affil-num=3 en-affil=School of Science,Tokyo Institute of Technology kn-affil= affil-num=4 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=6 en-affil=School of Materials and Chemical Technology, Tokyo Institute of Technology kn-affil= affil-num=7 en-affil=School of Science,Tokyo Institute of Technology kn-affil= affil-num=8 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=9 en-affil=Department of Chemistry & Biotechnology, School of Engineering, The University of Tokyo kn-affil= END start-ver=1.4 cd-journal=joma no-vol=59 cd-vols= no-issue=SK article-no= start-page=SKKA06 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2020 dt-pub=20200406 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Design of non-circular membranes metasurfaces for broadband sound absorption en-subtitle= kn-subtitle= en-abstract= kn-abstract=Acoustic metasurfaces have been attracting much attention due to their effectiveness in controlling sound wave propagation despite a structure well below the wavelength at operating frequency. We propose a novel decorated membrane resonator structure with multiple circular membranes leading to multiplexing the resonant modes through breaking symmetry of the membrane's vibrational modes. By numerical analysis, the structure is optimized for wideband (500 to 1500 Hz) sound absorption. The designed structure is fabricated by using a 3D printer and its sound absorption property is verified experimentally by an impedance tube measurement. The results demonstrate that the present approach is simple but effective to broadband sound absorption with thin and lightweight artificial acoustic structures. en-copyright= kn-copyright= en-aut-name=WatanabeKeita en-aut-sei=Watanabe en-aut-mei=Keita kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=FujitaMikiya en-aut-sei=Fujita en-aut-mei=Mikiya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Okayama University kn-affil= affil-num=2 en-affil=Okayama University kn-affil= affil-num=3 en-affil=Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=10 cd-vols= no-issue=1 article-no= start-page=6486 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2020 dt-pub=20200416 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Whitish daytime radiative cooling using diffuse reflection of non-resonant silica nanoshells en-subtitle= kn-subtitle= en-abstract= kn-abstract=Daytime radiative cooling offers efficient passive cooling of objects by tailoring their spectral responses, holding great promise for green photonics applications. A specular reflector has been utilized in cooling devices to minimize sunlight absorption, but such a glaring surface is visually less appealing, thus undesirable for public use. Here, by exploiting strong diffuse reflection of silica nanoshells in a polymer matrix, daytime radiative cooling below the ambient temperature is experimentally demonstrated, while showing whitish color under sunlight. The cooling device consists of a poly(methyl methacrylate) layer with randomly distributed silica nanoshells and a polydimethylsiloxane (PDMS) layer on an Ag mirror. The non-resonant nanoshells exhibit uniform diffuse reflection over the solar spectrum, while fully transparent for a selective thermal radiation from the underneath PDMS layer. In the temperature measurement under the sunlight irradiation, the device shows 2.3 degrees C cooler than the ambient, which is comparable to or even better than the conventional device without the nanoshells. Our approach provides a simple yet powerful nanophotonic structure for realizing a scalable and practical daytime radiative cooling device without a glaring reflective surface. en-copyright= kn-copyright= en-aut-name=SuichiTakahiro en-aut-sei=Suichi en-aut-mei=Takahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=IshikawaAtsushi en-aut-sei=Ishikawa en-aut-mei=Atsushi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TanakaTakuo en-aut-sei=Tanaka en-aut-mei=Takuo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=HayashiYasuhiko en-aut-sei=Hayashi en-aut-mei=Yasuhiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name=Œ’“๑ kn-aut-sei= kn-aut-mei=Œ’“๑ aut-affil-num=5 ORCID= affil-num=1 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=2 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=3 en-affil=Metamaterials Laboratory, RIKEN Cluster for Pioneering Research kn-affil= affil-num=4 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=5 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=117 cd-vols= no-issue=10 article-no= start-page=101103 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2020 dt-pub=20200909 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Super-chiral vibrational spectroscopy with metasurfaces for high-sensitive identification of alanine enantiomers en-subtitle= kn-subtitle= en-abstract= kn-abstract=Chiral nature of an enantiomer can be characterized by circular dichroism (CD) spectroscopy, but such a technique usually suffers from weak signal even with a sophisticated optical instrument. Recent demonstrations of plasmonic metasurfaces showed that chiroptical interaction of molecules can be engineered, thereby greatly simplifying a measurement system with high sensing capability. Here, by exploiting super-chiral field in a metasurface, we experimentally demonstrate high-sensitive vibrational CD spectroscopy of alanine enantiomers, the smallest chiral amino acid. Under linearly polarized excitation, the metasurface consisting of an array of staggered Au nano-rods selectively produces the left- and right-handed super-chiral fields at 1600?cm?1, which spectrally overlaps with the functional group vibrations of alanine. In the Fourier-transform infrared spectrometer measurements, the mirror symmetric CD spectra of D- and L-alanine are clearly observed depending on the handedness of the metasurface, realizing the reliable identification of small chiral molecules. The corresponding numerical simulations reveal the underlying resonant chiroptical interaction of plasmonic modes of the metasurface and vibrational modes of alanine. Our approach demonstrates a high-sensitive vibrational CD spectroscopic technique, opening up a reliable chiral sensing platform for advanced infrared inspection technologies. en-copyright= kn-copyright= en-aut-name=IidaTakumi en-aut-sei=Iida en-aut-mei=Takumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=IshikawaAtsushi en-aut-sei=Ishikawa en-aut-mei=Atsushi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TanakaTakuo en-aut-sei=Tanaka en-aut-mei=Takuo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MuranakaAtsuya en-aut-sei=Muranaka en-aut-mei=Atsuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=UchiyamaMasanobu en-aut-sei=Uchiyama en-aut-mei=Masanobu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=HayashiYasuhiko en-aut-sei=Hayashi en-aut-mei=Yasuhiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= affil-num=1 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=2 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=3 en-affil=Metamaterials Laboratory, RIKEN Cluster for Pioneering Research kn-affil= affil-num=4 en-affil=Advanced Elements Chemistry Laboratory, RIKEN Cluster for Pioneering Research kn-affil= affil-num=5 en-affil=Advanced Elements Chemistry Laboratory, RIKEN Cluster for Pioneering Research kn-affil= affil-num=6 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=7 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=60 cd-vols= no-issue=SD article-no= start-page=SDDA01 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2021 dt-pub=20210222 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Low-frequency sound absorbing metasurface using multilayer split resonators en-subtitle= kn-subtitle= en-abstract= kn-abstract=Among the acoustic metasurfaces that can control the propagation of sound waves with the structure far thinner than the wavelength at the operating frequency, the split tube structure has shown its effectiveness in the lower frequency band. Here we focus on multiply layered split tubes to broaden the absorption spectrum. By numerical analysis, we show up-to six-layer structure possessing wideband (1?1000 Hz) sound absorption. The absorbing peaks in the frequency band below 1000 Hz are shown to be multiplexed not only by simple superposition of vibrational modes of each layer, but also by hybridization of the modes indicating collective motion of tubes. en-copyright= kn-copyright= en-aut-name=TakasugiShota en-aut-sei=Takasugi en-aut-mei=Shota kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=WatanabeKeita en-aut-sei=Watanabe en-aut-mei=Keita kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MisawaMasaaki en-aut-sei=Misawa en-aut-mei=Masaaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=2 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=3 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=4 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=20 cd-vols= no-issue=4 article-no= start-page=261 end-page=265 dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20220806 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=First-principles Analysis of Stearic Acid Adsorption on Calcite (104) Surface en-subtitle= kn-subtitle= en-abstract= kn-abstract=Calcium carbonate nanoparticles are often surface-treated with organic compounds such as fatty acids. The activated calcium carbonates not only exhibit excellent application properties, but also can be applied as eco-friendly inorganic-organic hybrid materials. However, the microscopic adsorption structure of organic compounds on calcite surfaces is not yet well understood. In this study, we performed computational simulations based on density functional theory to investigate adsorption states of stearic acid (SA) on a calcite (104) surface. Based on the first-principles ionic relaxation and molecular dynamics simulations for several types of SA?SA and calcite?SA bonding models, a SA bilayer model on the calcite (104) surface is predicted to be a possible stable structure. The proposed structure model is well consistent with the experimentally predicted adsorption mechanism of SA on the calcite (104) surface. en-copyright= kn-copyright= en-aut-name=MachidaNarumi en-aut-sei=Machida en-aut-mei=Narumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=MisawaMasaaki en-aut-sei=Misawa en-aut-mei=Masaaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KezukaYuki en-aut-sei=Kezuka en-aut-mei=Yuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Faculty of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Shiraishi Central Laboratories Co., Ltd. kn-affil= affil-num=4 en-affil=Faculty of Natural Science and Technology, Okayama University kn-affil= en-keyword=Calcite kn-keyword=Calcite en-keyword=Stearic acid kn-keyword=Stearic acid en-keyword=Surface adsorption kn-keyword=Surface adsorption en-keyword=Density functional calculation kn-keyword=Density functional calculation en-keyword=Molecular dynamics kn-keyword=Molecular dynamics END start-ver=1.4 cd-journal=joma no-vol=14 cd-vols= no-issue=10 article-no= start-page=2133 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20221013 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Design and Robustness Evaluation of Valley Topological Elastic Wave Propagation in a Thin Plate with Phononic Structure en-subtitle= kn-subtitle= en-abstract= kn-abstract=Based on the concept of band topology in phonon dispersion, we designed a topological phononic crystal in a thin plate for developing an efficient elastic waveguide. Despite that various topological phononic structures have been actively proposed, a quantitative design strategy of the phononic band and its robustness assessment in an elastic regime are still missing, hampering the realization of topological acoustic devices. We adopted a snowflake-like structure for the crystal unit cell and determined the optimal structure that exhibited the topological phase transition of the planar phononic crystal by changing the unit cell structure. The bandgap width could be adjusted by varying the length of the snow-side branch, and a topological phase transition occurred in the unit cell structure with threefold rotational symmetry. Elastic waveguides based on edge modes appearing at interfaces between crystals with different band topologies were designed, and their transmission efficiencies were evaluated numerically and experimentally. The results demonstrate the robustness of the elastic wave propagation in thin plates. Moreover, we experimentally estimated the backscattering length, which measures the robustness of the topologically protected propagating states against structural inhomogeneities. The results quantitatively indicated that degradation of the immunization against the backscattering occurs predominantly at the corners in the waveguides, indicating that the edge mode observed is a relatively weak topological state. en-copyright= kn-copyright= en-aut-name=KataokaMotoki en-aut-sei=Kataoka en-aut-mei=Motoki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=MisawaMasaaki en-aut-sei=Misawa en-aut-mei=Masaaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=2 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= affil-num=3 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= en-keyword=phononic crystal kn-keyword=phononic crystal en-keyword=topological acoustic kn-keyword=topological acoustic en-keyword=elastic waveguide kn-keyword=elastic waveguide en-keyword=backscattering length kn-keyword=backscattering length en-keyword=lamb wave kn-keyword=lamb wave END start-ver=1.4 cd-journal=joma no-vol=62 cd-vols= no-issue=SJ article-no= start-page=SJ0803 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2023 dt-pub=20230427 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Acoustic metasurfaces and topological phononics for acoustic/elastic device design en-subtitle= kn-subtitle= en-abstract= kn-abstract=This paper reviews recent progress in acoustic metasurfaces and the novel concept of "topological acoustic/phononics" for designing compact yet efficient acoustic devices. After a brief review of this research area and its impact on ultrasonic technologies, some of the efforts to develop highly efficient sound absorption devices using acoustic metasurfaces are introduced. A resonance-based mechanism to achieve efficient absorption in metasurface structures thinner than the wavelength of the incident sound is briefly discussed, and its extensions to a broad spectrum are highlighted. Next, a valley topological phononic system is introduced, and its applications to the design of phononic waveguides are exemplified. The band structure design for extracting topologically protected edge modes is shown together with a numerical and experimental demonstration of the robustness of phononic waveguides constructed in both acoustic and elastic regimes. en-copyright= kn-copyright= en-aut-name=TsurutaKenji en-aut-sei=Tsuruta en-aut-mei=Kenji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= affil-num=1 en-affil=Department of Electrical and Electronic Engineering, Okayama University kn-affil= END