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Miura, Daisuke*; Kumada, Takayuki; Sekine, Yurina; Motokawa, Ryuhei; Nakagawa, Hiroshi; Oba, Yojiro; Ohara, Takashi; Takata, Shinichi; Hiroi, Kosuke; Morikawa, Toshiaki*; et al.
Journal of Applied Crystallography, 54(2), p.454 - 460, 2021/04
Times Cited Count：1 Percentile：17.63(Chemistry, Multidisciplinary)We developed a spin-contrast-variation neutron powder diffractometry technique that extracts the structure factor of hydrogen atoms, namely, the contribution of hydrogen atoms to a crystal structure factor. Crystals of L-glutamic acid were dispersed in a dpolystyrene matrix containing 4-methacryloyloxy-2,2,6,6,-tetramethyl-1-piperidinyloxy (TEMPO methacrylate) to polarize their proton spins dynamically. The intensities of the diffraction peaks of the sample changed according to the proton polarization, and the structure factor of the hydrogen atoms was extracted from the proton-polarization dependent intensities. This technique is expected to enable analyses of the structures of hydrogen-containing materials that are difficult to determine with conventional powder diffractometry.
Shinohara, Yasushi*; Otobe, Tomohito; Iwata, Junichi*; Yabana, Kazuhiro*
Nihon Butsuri Gakkai-Shi, 67(10), p.685 - 689, 2012/10
Coherent phonon is the macroscopic coherent oscillation of atoms in a solid state generating under the ultrafast laser pulse which is shorter than the frequency of the phonon. Some physical processes for the coherent phonon have been proposed. We are studying the computational method describing the dynamics of the electron and atom employing the time-dependent density functional theory. Our computational results show the origine of the coherent phonon in Si quantitatively.
Shinohara, Yasushi*; Sato, Shunsuke*; Yabana, Kazuhiro*; Iwata, Junichi*; Otobe, Tomohito; Bertsch, G. F.*
Journal of Chemical Physics, 137(22), p.22A527_1 - 22A527_8, 2012/08
Times Cited Count：25 Percentile：67.85(Chemistry, Physical)The time-dependent density functional theory (TDDFT) is the leading computationally feasible theory to treat excitations by strong electromagnetic fields. Here the theory is applied to coherent optical phonon generation. We examine the process in the crystalline semimetal antimony (Sb), where nonadiabatic coupling and optical phonon of different symmetries can be observed. The TDDFT is able to account for a number of qualitative features of the observed coherent phonon.
Yabana, Kazuhiro*; Shinohara, Yasushi*; Otobe, Tomohito; Iwata, Junichi*; Bertsch, G. F.*
Procedia Computer Science, 4, p.852 - 859, 2011/00
Times Cited Count：2 Percentile：60.86(Computer Science, Theory & Methods)We report a first-principle computational method to describe many-electron dynamics in crystalline solid. The method is based on the time-dependent density functional theory, solving time-dependent Kohn-Sham equation in real-time and real-space. The calculation is efficiently parallelized by distributing computations of different 
-point among processors. To illustrate usefulness of the method and efficiency of the parallel computation, we show calculations of electron dynamics in bulk Si induced by intense and ultrafast laser pulse.
Shinohara, Yasushi*; Yabana, Kazuhiro*; Kawashita, Yosuke*; Iwata, Junichi*; Otobe, Tomohito; Bertsch, G. F.*
Physical Review B, 82(15), p.155110_1 - 155110_10, 2010/10
Times Cited Count：63 Percentile：88.63(Materials Science, Multidisciplinary)We apply the adiabatic time-dependent density functional theory (TDDFT) to the generation of coherent optical phonons in Si crystals by intense laser pulses. The theory reproduces the main phenomena observed experimentally: dependence on polarization, strong growth at the direct band gap, and the change in phase from below to above the band gap. Both show that two mechanisms invoked in phenomenological theory, namely, impulsively stimulated Raman scattering and displacive excitation, are present in the TDDFT. The calculated phase of the coherent phonon is in qualitative agreement with experiment and with phenomenological modeling in the vicinity of the direct band gap. At higher laser frequencies, the TDDFT predicts additional structure not present in the modeling.
Shinohara, Yasushi*; Kawashita, Yosuke*; Iwata, Junichi*; Yabana, Kazuhiro*; Otobe, Tomohito; Bertsch, G. F.*
Journal of Physics; Condensed Matter, 22(38), p.384212_1 - 384212_4, 2010/09
Times Cited Count：13 Percentile：50.83(Physics, Condensed Matter)We report a first-principle description for coherent phonon generation in diamond based on the time-dependent density functional theory. The time-dependent Kohn-Sham equation is solved in real-time to calculate the electron dynamics in periodic solid under an ultrashort laser pulse. We find the calculated forces acting on ions are consistent with measurements in selection rule and in dependence on laser intensity.
Otobe, Tomohito; Yabana, Kazuhiro*; Iwata, Junichi*
Journal of Computational and Theoretical Nanoscience, 6(12), p.2545 - 2549, 2009/12
Times Cited Count：7 Percentile：33.2(Chemistry, Multidisciplinary)The nonlinear electron dynamics in the diamond crystal under the intense laser field is considered. We employ the time-dependent density-functional theory solving the time-dependent Kohn-Sham equation in real time and real space. We found the high harmonic generation from diamond up to 11th order with the laser intensity 
W/cm
and the induced field from surface charge suppress the harmonic generation strongly.
Otobe, Tomohito; Yabana, Kazuhiro*; Iwata, Junichi*
Journal of Physics; Condensed Matter, 21(6), p.064224_1 - 064224_5, 2009/02
Times Cited Count：48 Percentile：83.39(Physics, Condensed Matter)We present the first-principles description for electron dynamics in crystalline SiO induced by a spatially uniform external electric field. We rely upon the time-dependent density-functional theory with the adiabatic local-density approximation and a real-space and real-time method is employed to solve the time-dependent Kohn-Sham equation. The calculations are achieved for both weak and intense regimes. The response to the weak field provides us with the information on dielectric function, while the response to the intense field shows optical dielectric breakdown. We discuss the critical threshold for the dielectric breakdown of crystalline SiO, in comparison with the results for diamond.
Otobe, Tomohito; Yamagiwa, Mitsuru; Iwata, Junichi*; Yabana, Kazuhiro*; Nakatsukasa, Takashi*; Bertsch, G. F.*
Physical Review B, 77(16), p.165104_1 - 165104_5, 2008/04
Times Cited Count：154 Percentile：96.78(Materials Science, Multidisciplinary)We present a first-principle calculation for optical dielectric breakdown induced by an intense laser field. We employ the time-dependent density-functional theory, solving the time-dependent Kohn-Sham equation in real time and real space. The calculation shows a qualitative change of electron dynamics as the laser intensity increase, above 7
10
W/cm. Following the pulse, the excited electron exhibit a coherent plasma oscillation.
Otobe, Tomohito; Yamagiwa, Mitsuru; Iwata, Junichi*; Yabana, Kazuhiro*; Nakatsukasa, Takashi*; Bertsch, G. F.*
RIKEN Accelerator Progress Report, Vol.41, P. 185, 2008/00
We simulate the optical breakdown process of dielectrics under the intense laser field employing the first-principle method. Our result for the diamond, which is typical dielectrics, shows the saturation of the energy absorption and electron excitation. We found also the induced field by the surface charge becomes out of phase to the applied field.
Kaji, Yoshiyuki; Tsukada, Takashi; Fujita, Mitsutane*; Kinugawa, Junichi*; Yoshida, Kenji*; Mashiko, Shinichi*; Onose, Shoji*; Iwata, Shuichi*
2003-Nen Johogaku Shimpojiumu Koen Rombunshu, p.89 - 92, 2003/01
The distributed material database system named 'Data-Free-Way' has been developed by four organizations (the National Institute for Materials Science, the Japan Atomic Energy Research Institute, the Japan Nuclear Cycle Development Institute, and the Japan Science and Technology Corporation) under a cooperative agreement. In order to create additional values of the system, knowledge base system, in which knowledge extracted from the material database is expressed, is planned to be developed for more effective utilization of Data-Free-Way. XML (eXtensible Markup Language) has been adopted as the description method of the retrieved results and the meaning of them. This paper will describe the description method of knowledge extracted from the material database with XML and the distributed material knowledge base system.
Kaji, Yoshiyuki; Yoshida, Kenji*; Mashiko, Shinichi*; Fujita, Mitsutane*; Shimura, Kazuki*; Kinugawa, Junichi*; Tsuji, Hirokazu; Miyakawa, Shunichi*; Iwata, Shuichi*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 1(4), p.412 - 418, 2002/12
The distributed material database system named 'Data-Free-Way' has been developed by four organizations (the National Institute for Materials Science, the Japan Atomic Energy Research Institute, the Japan Nuclear Cycle Development Institute, and the Japan Science and Technology Corporation) under a cooperative agreement. In order to create additional values of the system, knowledge base system, in which knowledge extracted from the material database is expressed, is planned to be developed for more effective utilization of Data-Free-Way. XML (eXtensible Markup Language) has been adopted as the description method of the retrieved results and the meaning of them. One knowledge note described with XML is stored as one knowledge which composes the knowledge base. This paper describes the current status of Data-Free-Way, the description method of knowledge extracted from the material database with XML and the distributed material knowledge base system.
Tsuji, Hirokazu; Kaji, Yoshiyuki; Fujita, Mitsutane*; Kinugawa, Junichi*; Yoshida, Kenji*; Mashiko, Shinichi*; Shimura, Kazuki*; Miyakawa, Shunichi*; Iwata, Shuichi*
Proceedings of 10th German-Japanese Workshop on Chemical Information, p.131 - 133, 2002/00
The distributed material database system named "Data-Free-Way" has been developed by four organizations (the National Institute for Materials Science, the Japan Atomic Energy Research Institute, the Japan Nuclear Cycle Development Institute and Japan Science and Technology Corporation) under a cooperative agreement. It is a system which can display the data which the user demands without considering the organization which stores data as a table and a graph. The knowledge of the forte of each organization based on the retrieval result from the fact database is made aiming at more highly developed use of this system. The development of the system by which the user can refer to the knowledge is advanced. Though the retrieval result from the fact database was displayed as a table and a graph, that is, the finding note where they were described and expressed with XML as knowledge.
Kaji, Yoshiyuki; Yoshida, Kenji*; Mashiko, Shinichi*; Fujita, Mitsutane*; Shimura, Kazuki*; Kinugawa, Junichi*; Tsuji, Hirokazu; Miyakawa, Shunichi*; Iwata, Shuichi*
Dai-38-Kai Joho Kagaku Gijutsu Kenkyu Shukai Happyo Yokoushu, p.43 - 47, 2001/00
A distributed database system named Data-Free-Way for advanced nuclear materials has been developed by the National Institute for Materials Science (NIMS), the Japan Atomic Energy Research Institute (JAERI), the Japan Nuclear Cycle Development Institute (JNC), and the Japan Science and Technology Corporation (JST) under a cooperative agreement. In this system, end-users are able to obtain necessary data such as tables or graphs, even if they do not know the sites in which the data are stored. A distributed knowledge database in which each organization makes the knowledge based on the retrieval results from fact database and end-users can get the knowledge, has been developed to make more useful utilization of this system. Though the retrieval results from the fact database were shown in the tables or graphs, the new system constitutes the information notes described the retrieval ones for the knowledge by XML. This paper describes the present status of the Data-Free-Way and the description method of XML for the retrieval results.
Fujita, Mitsutane*; Kinugawa, Junichi*; Tsuji, Hirokazu; Kaji, Yoshiyuki; Tachi, Yoshiaki*; Saito, Junichi*; Shimura, Kazuki*; Nakajima, Ritsuko*; Iwata, Shuichi*
Fusion Engineering and Design, 51-52, p.769 - 774, 2000/11
Times Cited Count：1 Percentile：12.1(Nuclear Science & Technology)no abstracts in English
Kinugawa, Junichi*; Fujita, Mitsutane*; Noda, Tetsuji*; Tsuji, Hirokazu; Kaji, Yoshiyuki; Sakino, Takao*; Tachi, Yoshiaki*; Kaneda, Kenichiro*; Mashiko, Shinichi*; Shimura, Kazuki*; et al.
Proceedings of 9th German-Japanese Workshop on Chemical Information, p.134 - 135, 2000/00
no abstracts in English
Kaji, Yoshiyuki; Tsuji, Hirokazu; Sakino, Takao*; Fujita, Mitsutane*; Kinugawa, Junichi*; Tachi, Yoshiaki*; Saito, Junichi*; Kano, Shigeki*; Shimura, Kazuki*; Nakajima, Ritsuko*; et al.
JAERI-Tech 99-007, 32 Pages, 1999/02
no abstracts in English
Otobe, Tomohito; Yamagiwa, Mitsuru; Yabana, Kazuhiro*; Iwata, Junichi*; Nakatsukasa, Takashi*; Bertsch, G. F.*
no journal, ,
no abstracts in English
under the intense laser fieldOtobe, Tomohito; Yabana, Kazuhiro*; Iwata, Junichi*
no journal, ,
no abstracts in English
and the intense short pulse laserOtobe, Tomohito; Yabana, Kazuhiro*; Iwata, Junichi*
no journal, ,
The optical breakdown of transparent material under the intense laser field has been attracted much interest. We employ the time-dependent density-functional theory to calculate the electron dynamics and the excitation in the SiO, which is the major material as the future photonic device, under the intense laser field. We would like to present our computational results and the effect of the crystal and the band structure on the optical breakdown process.
