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@INPROCEEDINGS{DiNapoli:21585,
      author       = {Di Napoli, E.},
      title        = {{E}igenproblems and {E}igensolvers in {D}ensity
                      {F}unctional {T}heory},
      reportid     = {PreJuSER-21585},
      year         = {2012},
      note         = {Record converted from VDB: 12.11.2012},
      comment      = {Seminar at Argonne Leadership Computing Facility},
      booktitle     = {Seminar at Argonne Leadership
                       Computing Facility},
      abstract     = {In DFT based simulations each SCF cycle comprises dozens of
                      large generalized eigenproblems. In a recent study, it has
                      been proposed to consider simulations as made of dozens of
                      sequences of eigenvalue problems, where each sequence groups
                      together eigenproblems with equal k-vector and increasing
                      iteration index i. It was then demonstrated that successive
                      eigenproblems in a sequence are strongly correlated to one
                      another. In particular, by tracking the evolution over
                      iterations of the angle between eigenvectors of adjacent
                      iterations, it was shown the angles decrease noticeably
                      after the first few iterations and become close to
                      collinear. This last result suggests we could use the
                      eigenvectors solution of a problem in a sequence as an
                      educated guess for the eigenvectors of the successive
                      problem. In this talk we present preliminary results that
                      would eventually open the way to a widespread use of
                      iterative solvers in ab initio electronic structure codes.
                      We provide numerical examples where opportunely selected
                      iterative solvers benefit from the reuse of eigenvectors
                      when applied to sequences of eigenproblems extracted from
                      simulations of real-world materials.},
      month         = {Apr},
      date          = {2012-04-05},
      organization  = {Argonne, USA, 5 Apr 2012},
      subtyp        = {Invited},
      cin          = {JSC},
      cid          = {I:(DE-Juel1)JSC-20090406},
      pnm          = {Scientific Computing / Simulation and Data Laboratory
                      Quantum Materials (SDLQM) (SDLQM)},
      pid          = {G:(DE-Juel1)FUEK411 / G:(DE-Juel1)SDLQM},
      typ          = {PUB:(DE-HGF)31},
      url          = {https://juser.fz-juelich.de/record/21585},
}