| Project/Area Number |
07044066
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | The University of Tokyo |
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Principal Investigator |
UEDA Kazuo Institute for Solid State Physics, University of Tokyo, Professor, 物性研究所, 教授 (70114395)
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| Co-Investigator(Kenkyū-buntansha) |
CAR Robert Institut Romand de Recherche Numerique en Physique des Materiaux (IRRMA) and Uni, 教授
KONTANI Hiroshi Institute for Solid State Physics, University of Tokyo, 物性研究所, 助手 (90272533)
FURUKAWA Nobuo Institute for Solid State Physics, University of Tokyo, 物性研究所, 助手 (00238669)
NISHINO Tomotoshi Department of Physics, Kobe University, 理学部, 講師 (00241563)
OGITSU Tadashi Institute for Solid State Physics, University of Tokyo, 物性研究所, 助手 (20262165)
TSUNETSUGU Hirokazu Institute of Applied Physics, University of Tsukuba, 物性光学系, 助教授 (80197748)
TSUNEYUKI Shinji Institute for Solid State Physics, University of Tokyo, 物理工学所, 助教授 (90197749)
IMADA Masatoshi Institute for Solid State Physics, University of Tokyo, 物性研究所, 助教授 (70143542)
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| Project Period (FY) |
1995 – 1996
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| Keywords | condensed matter / many-body problem / strongly correlated electron system / metal-insulator transition / spin gap / quantum Monte Carlo simulation / density matrix renormalization group / ab-initio calculations |
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| Research Abstract |
The international collaboration on the spin gap phase of the plaquette RVB state has started during the period of this project and has been evolved into the study on the critical behavior of the quantum phase transition between the Neel ordered phase and the plaquette RVB phase. By employing the quantum loop algorithm Monte Carlo simulations it is shown that the critical exponents agree with the classical O (3) exponents, which supports the mapping to the nonlinear sigma model.
Another important problem studied in this project is the metal-insulator transition in two-dimension. By using quantum Monte Carlo simulations and the scaling theory, it is concluded that the hyperscaling hypothesis is valid in this case and the dynamical exponent is z=4.
Concerning the heavy Fermions, the one-dimensional Kondo lattice model was investigated by using the density matrix renormalization group. In the paramagnetic metallic phase, spin and charge Friedel oscillations were observed for the first time. From the period of oscillations it is concluded that the Fermi surface is large in the sense that the Fermi momentum is determined by the sum of densities of conduction electrons and the localized spins.
For the ab-initio calculations of electronic states, the constant pressure molecular dynamics method was developed. This method enables us to determine the transition states of structural transformations in graphite, silicides, BC_2N and others.
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