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2004 Fiscal Year Final Research Report Summary

Combination of First Principle Electronic Structure Theory and Many Electron Theory

Research Project

Project/Area Number 14540352
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 物性一般(含基礎論)
Research InstitutionThe University of Tokyo

Principal Investigator

FUJIWARA Takeo  The University of Tokyo, School of Engineering, Professor, 大学院・工学系研究科, 教授 (90011113)

Co-Investigator(Kenkyū-buntansha) YAMAMOTO Susumu  The University of Tokyo, School of Engineering, Research Associate, 大学院・工学系研究科, 助手 (30262041)
HOSHI Takeo  The University of Tokyo, School of Engineering, Research Associate, 大学院・工学系研究科, 助手 (80272384)
Project Period (FY) 2002 – 2004
KeywordsLDA+U Method / GW Approximation / DMFT+LDA / Coulomb interaction / density fluctuation / Metal- Insulator Transition / LaMnO_3 / Parallel computation
Research Abstract

We have investigated the following topics in order to combine the first principle electronic structure theory and the many electron theory.
(1)Development of LDA+U method and its applications : This method includes, within the framework of the density functional theory, the effects of large fluctuation of charge and spin densities due to electron-electron interactions. We studied the electronic structure of La_<1-x>SrxNiO_4. We concluded that this system could not be treated by LDA or LDA+U and now is being investigated by the method of rigorous diagonalization of the many-body Hamiltonian.
(2)Development of the GW Approximation and its applications : GW approximation is the lowest order treatment of many electron perturbation theory. We developed the off-set method, the generalized product basis method, and the parallelization of program code. The method is applied to HfO and A-type antiferromagnetic LaMnO_3. Up to now, A-type antiferromagnetic LaMnO_3 is actually too large for the GW approximation. We developed the parallel code by using OpenMT. The resultant spectrum, band gap and magnetic moment show a good agreement with experimental ones. We also calculated the electron-electron interaction for both on-site and off-site on Mn atoms as a function of excitation energy.
(3)DMFT+LDA : DMFT (Dynamical Mean Field Theory) is the many electron theory and has been developed in order to discuss the metal-insulator transition. This theory shows the coherent dynamics due to charge and spin fluctuation near M-I transition. We combine the DMFT with the LDA with a help of the Iterative Perturbation Theory in multi-orbital case and discussed the critical values of U/W (the ratio of Coulomb interaction and band width) for the M-I transition. Also the IPT framework is generalized to the case of s, p and d bands. This is very promising method because, at the present stage, the application of the Monte Calro method to general Hamiltonian an that of the LDA is not fully established.

  • Research Products

    (12 results)

All 2005 2003 2002

All Journal Article (12 results)

  • [Journal Article] Orbital Nature of Ferromagnetic Magnons in Manganites2005

    • Author(s)
      Y.Endoh, H.Hiraka, Y.Tomioka, Y.Tokura, N.Nagaosa, T.Fujiwara
    • Journal Title

      Physical Review Letters 94

      Pages: 017206-1-017206-4

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Orbital Nature of Ferromagnetic Magnons in Manganites2005

    • Author(s)
      Y.Endoh, H.Hiraka, Y.Tomioka, Y.Tokura, N.Nagaosa, T.Fujiwara
    • Journal Title

      Phys.Rev.Lett. 94

      Pages: 017206

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Electronic structure and dielectric properties of cubic zirconia2003

    • Author(s)
      S.Kobayashi, A.Yamasaki, T.Fujiwara
    • Journal Title

      Japanese Journal of Applied Physics 42

      Pages: 6946-6950

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Generalization of the iterative perturbation theory and metal-insulator transition in multi-orbital Hubbard bands2003

    • Author(s)
      T.Fujiwara, S.Yamamoto, Y.Ishii
    • Journal Title

      Journal of Physical Society of Japan 72

      Pages: 777-780

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Electronic Structure of transition metal Fe, Ni and Cu in the GW approximation2003

    • Author(s)
      A.Yamasaki, T.Fujiwara
    • Journal Title

      Journal of Physical Society of Japan 72

      Pages: 607-610

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Electronic structure and dielectric properties of cubic zirconia2003

    • Author(s)
      S.Kobayashi, A.Yamasaki, T.Fujiwara
    • Journal Title

      Jpn.J.Appl.Phys.42 No.11

      Pages: 6946-6950

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Generalization of the iterative perturbation theory and metal-insulator transition in multi-orbital Hubbard bands2003

    • Author(s)
      T.Fujiwara, S.Yamamoto, Y.Ishii
    • Journal Title

      J.Phys.Soc.Jpn vol.72

      Pages: 777-780

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Electronic Structure of transition metal Fe,Ni and Cu in the GW approximation2003

    • Author(s)
      A.Yamasaki, T.Fujiwara
    • Journal Title

      J.Phys.Soc.Jpn vol.72

      Pages: 607-610

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Charge and spin order in RNiO_3 (R=Nd, Y) by LSDA+U method2002

    • Author(s)
      S.Yamamoto, T.Fujiwara
    • Journal Title

      Journal of Physical Society of Japan 71

      Pages: 1226-1229

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Electronic Structure of oxides MO (M=Mg, Ca, Ti, V) in the GW approximation2002

    • Author(s)
      A.Yamasaki, T.Fujiwara
    • Journal Title

      Physical Review B 66

      Pages: 245108-1-245108-9

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Charge and spin order in RNiO_3 (R=Nd,Y) by LSDA+U method2002

    • Author(s)
      S.Yamamoto, T.Fujiwara
    • Journal Title

      J.Phys.Soc.Jpn vol.71

      Pages: 1226-1229

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Electronic Structure of oxides MO (M=Mg,Ca,Ti,V) in the GW approximation2002

    • Author(s)
      A.Yamasaki, T.Fujiwara
    • Journal Title

      Phys.Rev.B 66

      Pages: 245108

    • Description
      「研究成果報告書概要(欧文)」より

URL: 

Published: 2007-12-13  

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