Faculty Profiles - TSURUTA Kenji

Papers - TSURUTA Kenji

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Structure and dynamics of Yukawa dusty plasmas and dusty plasma mixtures Reviewed

C. Totsuji, H. Totsuji, K. Tsuruta, K. Kamon, T. Kishimoto, T. Sasabe

Le Journal de Physique IV 10 ( PR5 ) Pr5 - 425 2000.3

Structures and structural transitions in strongly-coupled Yukawa dusty plasmas and mixtures Reviewed

H Totsuji, C Totsuji, K Tsuruta

FRONTIERS IN DUSTY PLASMAS 141 - 146 2000

Language：English Publishing type：Research paper (international conference proceedings) Publisher：ELSEVIER SCIENCE BV

Regarded as Yukawa systems in external confining potentials, structures and transitions in dusty plasmas have been analyzed theoretically and by numerical simulations. The one-dimensional confinement in three dimensions and the radial confinement in two dimensions are considered. The results of simulations have been reproduced to a good accuracy in both cases. It is shown that the inclusion of the correlation energy or the effect of strong coupling is of essential importance in the theory. A crossover from the surface freezing of Coulomb system to surface melting of systems of short-ranged interactions is observed.

Intercluster interaction of TiO2 nanoclusters using variable-charge interatomic potentials Reviewed

S Ogata, H Iyetomi, K Tsuruta, F Shimojo, RK Kalia, A Nakano, P Vashishta

NANOPHASE AND NANOCOMPOSITE MATERIALS III 581 667 - 672 2000

Language：English Publishing type：Research paper (international conference proceedings) Publisher：MATERIALS RESEARCH SOCIETY

A new interatomic potential has been developed for molecular-dynamics simulations of TiO2 based on the formalism of Streitz and Mintmire [J. Adhesion Sci. Technol. 8, 853 (1994)], in which atomic charges vary dynamically according to the generalized electronegativity-equalization principle. The present potential reproduces various quantities of rutile crystal including vibrational density of states, static dielectric constants, melting temperature, elastic moduli, and surface relaxation. Calculated cohesive-energy and dielectric constants for anatase crystal agree well with experimental data The potential is applied to TiO2 nanoclusters (size 60-80 Angstrom) for both anatase and rutile phases to analyze their equilibrium configuration and space-charge distribution. Stable double-charge layer is found in the surface region of a spherical nanocluster for both rutile and anatase, resulting in enhanced Coulomb-repulsion between the nanoclusters at close proximity.

Other Link： http://orcid.org/0000-0002-1447-2530

Variable-charge interatomic potentials for molecular-dynamics simulations of TiO2 Reviewed

S Ogata, H Iyetomi, K Tsuruta, F Shimojo, RK Kalia, A Nakano, P Vashishta

JOURNAL OF APPLIED PHYSICS 86 ( 6 ) 3036 - 3041 1999.9

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER INST PHYSICS

An interatomic potential model has been developed for molecular-dynamics simulations of TiO2 (rutile) based on the formalism of Streitz and Mintmire [J. Adhes. Sci. Technol. 8, 853 (1994)], in which atomic charges vary dynamically according to the generalized electronegativity equalization principle. The present model potential reproduces the vibrational density of states, the pressure-dependent static dielectric constants, the melting temperature, and the surface relaxation of the rutile crystal, as well as the cohesive energy, the lattice constants, and the elastic moduli. We find the physical properties of rutile are significantly affected by dynamic charge transfer between Ti and O atoms. The potential allows us to perform atomistic simulations on nanostructured TiO2 with various kinds of interfaces (surfaces, grain boundaries, dislocations, etc.). (C) 1999 American Institute of Physics. [S0021-8979(99)07618-5].

DOI： 10.1063/1.371165

Other Link： http://orcid.org/0000-0002-1447-2530

Parallel molecular dynamics simulations of high temperature ceramics Reviewed

A Chatterjee, T Campbell, RK Kalia, A Nakano, A Omeltchenko, K Tsuruta, P Vashishta, S Ogata

JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 19 ( 13-14 ) 2257 - 2264 1999

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCI LTD

'Grand Challenge' atomistic simulations of high-temperature structural materials ave performed on multiple, parallel platforms. The simulations focus on sintering of ceramic nanoclusters, structure and mechanical properties of nanophase ceramics, and hypervelocity impact damage in diamond coatings. (C) 1999 Elsevier Science Ltd. All rights reserved.

Structures and dynamics of dusty plasmas and dusty plasma mixtures Reviewed

H Totsuji, C Totsuji, K Tsuruta, K Kamon, T Kishimoto, T Sasabe

NON-NEUTRAL PLASMA PHYSICS III 498 389 - 394 1999

Language：English Publishing type：Research paper (international conference proceedings) Publisher：AMER INST PHYSICS

Dusty plasmas can be regarded as assemblies of Yukawa particles in a one-dimensional potential well. We extend the analyses on dusty plasmas in two directions: the two-dimensional Yukawa system and Yukawa mixtures. (1) Under appropriate conditions at low temperatures, dust particles sit in a plane which is perpendicular to the gravitational field. When they are also confined laterally by an electrode, we have a finite two-dimensional system of Yukawa particles. The low temperature structures are obtained by molecular dynamics simulations and the results are reproduced by theoretical analyses. Through these analyses we show that the correlation energy of the Yukawa system plays an essential role in structure formations. As for dynamics of this system, a crossover from the surface freezing of Coulomb system to surface melting of systems of short-ranged interactions is observed. (2) In the case of mixtures, we have an extra parameter characterizing the difference in the gravity on each species. We obtain the low temperature structures of this system and compare them with theoretical predictions based on the results for the case of one component.

Two-component nonequilibrium nonneutral plasma in Penning-Malmberg trap Reviewed

H Totsuji, K Tsuruta, C Totsuji, K Nakano, K Kamon, T Kishimoto

NON-NEUTRAL PLASMA PHYSICS III 498 77 - 82 1999

Language：English Publishing type：Research paper (international conference proceedings) Publisher：AMER INST PHYSICS

The behavior of the two-component nonneutral plasma in the Penning Malmberg trap is analyzed by simulations and theoretical approaches. The parameters expected in experiments of antiproton cooling by electrons are assumed. The relaxation of antiproton energy is followed by the rate equation with proper account taken into account for the slow transfer of energy between parallel and perpendicular components of strongly magnetized electrons. The equilibrium distribution of each species are obtained by molecular dynamics simulations for various Values of parameters and the results are reproduced by theoretical calculations to a good accuracy. The condition for the centrifugal separation is obtained.

Structural correlations and mechanical behavior in nanophase silica glasses Reviewed

T. J. Campbell, R. K. Kalia, A. Nakano, F. Shimojo, K. Tsuruta, P. Vashishta, S. Ogata

Physical Review Letters 82 ( 20 ) 4018 - 4021 1999

Structure and dynamics of consolidation and fracture in nanophase ceramics via parallel molecular dynamics Reviewed

K Tsuruta, JH Wang, A Omeltchenko, A Nakano, RK Kalia, P Vashishta

COMPUTER-AIDED DESIGN OF HIGH-TEMPERATURE MATERIALS 323 - 332 1999

Structural correlations and stress distribution at silicon/silicon nitride interface Reviewed

ME Bachlechner, A Omeltchenko, K Tsuruta, A Nakano, RK Kalia, P Vashishta, Ebbsjo, I, A Madhukar

COMPUTER-AIDED DESIGN OF HIGH-TEMPERATURE MATERIALS 244 - 255 1999

Dynamic fracture in nanophase ceramics and diamond films: Multimillion atom parallel molecular-dynamics simulations Reviewed

A Omeltchenko, K Tsuruta, A Nakano, R Kalia, P Vashishta, O Shenderova, DW Brenner

COMPUTER-AIDED DESIGN OF HIGH-TEMPERATURE MATERIALS 81 - 104 1999

Atomistic simulation of nanostructured materials Reviewed

A Nakano, ME Bachlechner, TJ Campbell, RK Kalla, A Omeltchenko, K Tsuruta, P Vashishta, S Ogata, Ebbsjo, I, A Madhukar

IEEE COMPUTATIONAL SCIENCE & ENGINEERING 5 ( 4 ) 68 - 78 1998.10

Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE COMPUTER SOC

Materials and devices with microstructures on the nanometer scale are revolutionizing technology, but until recently simulation at this scale has bean problematic. Developments in parallel computing are now allowing atomistic simulation using multiresolution algorithms, such as fast multipole methods. With these algorithms, researchers may soon be able to simulate applications up to one billion atoms.

DOI： 10.1109/99.735897

Dynamics of consolidation and crack growth in nanocluster-assembled amorphous silicon nitride Reviewed

K Tsuruta, A Nakano, RK Kalia, P Vashishta

JOURNAL OF THE AMERICAN CERAMIC SOCIETY 81 ( 2 ) 433 - 436 1998.2

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CERAMIC SOC

Consolidation and fracture dynamics in nanophase amorphous Si3N4 are investigated using 10(6)-atom molecular-dynamics simulations. At a pressure of 15 GPa and 2000 K, the nanophase system is almost fully consolidated within a fraction of a nanosecond. The consolidation process is well-described by the classical theory of sintering. Under an applied strain the consolidated system develops several cracks which propagate parallel to each other, causing failure at multiple sites. The critical strain at which the nanophase system fractures is much larger than that for crystalline Si3N4.

Oxidation dynamics of nanophase aluminum clusters: A molecular dynamics study Reviewed

S Ogata, TJ Campbell, K Tsuruta, A Nakano, RK Kalia, P Vashishta, CK Loong

PHASE TRANSFORMATIONS AND SYSTEMS DRIVEN FAR FROM EQUILIBRIUM 481 625 - 630 1998

Language：English Publishing type：Research paper (international conference proceedings) Publisher：MATERIALS RESEARCH SOCIETY

Oxidation of an aluminum nanocluster (252,158 atoms) of radius 100 Angstrom placed in gaseous oxygen (530,727 atoms) is investigated by performing molecular-dynamics simulations on parallel computers. The simulation takes into account the effect of charge transfer between Al and O based on the electronegativity equalization principles. We find that the oxidation starts at the surface of the cluster and the oxide layer grows to a thickness of similar to 28 Angstrom. Evolutions of local temperature and densities of Al and O are investigated. The surface oxide melts because of the high temperature resulting from the release of energy associated with Al-O bondings. Amorphous surface-oxides are obtained by quenching the cluster. Vibrational density-of-states for the surface oxide is analyzed through comparisons with those for crystalline Al, Al nanocluster, and alpha-Al2O3.

Other Link： http://orcid.org/0000-0002-1447-2530

Role of ultrafine microstructures in dynamic fracture in nanophase silicon nitride Reviewed

RK Kalia, A Nakano, A Omeltchenko, K Tsuruta, P Vashishta

PHYSICAL REVIEW LETTERS 78 ( 11 ) 2144 - 2147 1997.3

Language：English Publishing type：Research paper (scientific journal) Publisher：AMERICAN PHYSICAL SOC

Using 10(6)-atom molecular-dynamics simulations, we investigate dynamic fracture in nanophase Si3N4. The simulations reveal that intercluster regions are amorphous, and they deflect cracks and give rise to local crack branching. As a result, the nanophase system is able to sustain an order-of-magnitude larger external strain than crystalline Si3N4. We also determine the morphology of fracture surfaces: For in-plane fracture surface profiles the roughness exponent zeta = 0.57 and for out-of-plane profiles the exponents zeta(perpendicular to) = 0.84 and zeta(parallel to) = 0.75 are in excellent agreement with experiments.

Morphology of pores and interfaces and mechanical behavior of nanocluster-assembled silicon nitride ceramic Reviewed

RK Kalia, A Nakano, K Tsuruta, P Vashishta

PHYSICAL REVIEW LETTERS 78 ( 4 ) 689 - 692 1997.1

Language：English Publishing type：Research paper (scientific journal) Publisher：AMERICAN PHYSICAL SOC

Million atom molecular-dynamics simulations are performed to investigate the structure, dynamics, and mechanical behavior of cluster-assembled Si3N4. These solids contain highly disordered interfacial regions with 50% undercoordinated atoms. Systems sintered at low pressures have percolating pores whose surface morphologies are well characterized by two values of the roughness exponent, 0.46 and 0.86; these are close to the experimental values found by Bouchaud et al. for fracture surfaces. Results for elastic moduli are consistent with a three-phase model for heterogeneous materials.

Structure, mechanical properties, and dynamic fracture in nanophase silicon nitride via parallel molecular dynamics Reviewed

K Tsuruta, A Omeltchenko, A Nakano, RK Kalia, P Vashishta

NANOPHASE AND NANOCOMPOSITE MATERIALS II 457 205 - 210 1997

Language：English Publishing type：Research paper (international conference proceedings) Publisher：MATERIALS RESEARCH SOCIETY

Million-atom molecular-dynamics (MD) simulations are performed to study the structure, mechanical properties, and dynamic fracture in nanophase Si3N4. We find that intercluster regions are highly disordered: 50% of Si atoms in intercluster regions are three-fold coordinated. Elastic moduli of nanophase Si3N4 as a function of grain size and porosity are well described by a multiphase model for heterogeneous materials. The study of fracture in the nanophase Si3N4 reveals that the system can sustain an order-of-magnitude larger external load than crystalline Si3N4. This is due to branching and pinning of the crack front by nanoscale microstructures.

Other Link： http://orcid.org/0000-0002-1447-2530

Million atom molecular dynamics simulation of nanophase silicon nitride Reviewed

RK Kalia, A Nakano, A Omeltchenko, K Tsuruta, P Vashishta

CHEMISTRY AND PHYSICS OF NANOSTRUCTURES AND RELATED NON-EQUILIBRIUM MATERIALS 89 - 96 1997

Language：English Publishing type：Research paper (international conference proceedings) Publisher：MINERALS, METALS & MATERIALS SOC

Structural correlations and dynamic fracture in nanocluster-assembled silicon nitride are investigated with molecular-dynamics (MD) simulations involving 1.08 million particles. These simulations reveal that the consolidated nanophase Si3N4 has highly disordered intercluster regions that contain 50% under-coordinated atoms. Amorphous interfacial regions deflect cracks and give rise to local crack branching. These dissipative mechanisms enable the nanophase system to sustain an order-of-magnitude larger external strain than crystalline Si3N4. The morphology of fracture surfaces in nanophase Si3N4 is also determined. The MD results for roughness exponents are very close to experimental values even though the materials and length scales are very different.

Other Link： http://orcid.org/0000-0002-1447-2530

Fracture of nanophase ceramics: A molecular-dynamics study Reviewed

A Nakano, RK Kalia, A Omeltchenko, K Tsuruta, P Vashishta

NANOPHASE AND NANOCOMPOSITE MATERIALS II 457 187 - 192 1997

Language：English Publishing type：Research paper (international conference proceedings) Publisher：MATERIALS RESEARCH SOCIETY

New multiscale algorithms and a load-balancing scheme are combined for molecular-dynamics simulations of nanocluster-assembled ceramics on parallel computers. Million-atom simulations of the dynamic fracture in nanophase silicon nitride reveal anisotropic self-affine structures and crossover phenomena associated with fracture surfaces.

Other Link： http://orcid.org/0000-0002-1447-2530

Million atom molecular dynamics simulations of materials on parallel computers Reviewed

P Vashishta, RK Kalia, W Li, A Nakano, A Omeltchenko, K Tsuruta, JH Wang, Ebbsjo, I

CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE 1 ( 6 ) 853 - 863 1996.12

Language：English Publisher：CURRENT SCIENCE LTD

Recent advances in computing technology - parallel computer architectures, portable software and development of robust O(N) algorithms - have revolutionized the field of computer simulation. Using the space-time multiresolution molecular dynamics algorithms it is possible to carry out multimillion atom simulations of materials in different ranges of density, temperature and uniaxial strain.

DOI： 10.1016/S1359-0286(96)80113-6

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