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@BOOK{Baumeister:128376,
      author       = {Baumeister, Paul Ferdinand},
      title        = {{R}eal-{S}pace {F}inite-{D}ifference {PAW} {M}ethod for
                      {L}arge-{S}cale {A}pplications on {M}assively {P}arallel
                      {C}omputers},
      volume       = {53},
      school       = {RWTH Aachen},
      type         = {Dr. (Univ.)},
      address      = {Jülich},
      publisher    = {Foschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2013-00115},
      isbn         = {978-3-89336-836-5},
      series       = {Schriften des Forschungszentrums Jülich.
                      Schlüsseltechnologien / Key Technologies},
      pages        = {VI, 212 S.},
      year         = {2012},
      note         = {Schriftenreihen des Forschungszentrum Jülich; RWTH Aachen,
                      Diss., 2012},
      abstract     = {Simulations of materials from first principles have
                      improved drastically over the last few decades, benefitting
                      from newly developed methods and access to increasingly
                      large computing resources. Nevertheless, a quantum
                      mechanical description of a solid without approximations is
                      not feasible. In the wide field of methods for $\textit{ab
                      initio}$ calculations of electronic structure, it has become
                      apparent that density functional theory and, in particular,
                      the local density approximation can also make simulations of
                      large systems accessible. Density functional calculations
                      provide insight into the processes taking place in a vast
                      range of materials by their access to an understandable
                      electronic structure in the framework of the Kohn-Sham
                      single particle wave functions. A number of functionalities
                      in the fields of electronic devices, catalytic surfaces,
                      molecular synthesis and magnetic materials can be explained
                      by analyzing the resulting total energies, ground state
                      structures and Kohn-Sham spectra. However, challenging
                      physical problems are often accompanied by calculations
                      including a huge number of atoms in the simulation volume,
                      mostly due to very low symmetry. The total workload of
                      wave-function-based DFT scales at best quadraticallywith the
                      number of atoms. This means that supercomputersmust be used.
                      In the present work, an implementation of DFT on real-space
                      grids has been developed, suitable for making use of the
                      massively parallel computing resources of modern
                      supercomputers. Massively parallel machines are based on
                      distributed memory and huge numbers of compute nodes, easily
                      exceeding 100,000 parallel processes. An efficient
                      parallelization of density functional calculations is only
                      possible when the data can be stored process-local and the
                      amount of inter-node communication is kept low. Our
                      real-space grid approach with three-dimensional domain
                      decomposition provides an intrinsic data locality and solves
                      both the Poisson equation for the electrostatic problemand
                      the Kohn-Sham eigenvalue problem on a uniform real-space
                      grid. The derivative operators are approximated by finite
                      differences leading to localized operators which only
                      require communication with the nearest neighbor processes.
                      This leads to excellent parallel performance at large system
                      sizes. Treating only valence electrons, we apply the
                      projector-augmented wave method for accurate modeling of
                      energy contributions and scattering properties of the atomic
                      cores. In addition to real-space grid parallelization, we
                      apply a distribution of the workload of different Kohn-Sham
                      states onto parallel processes. This second parallelization
                      level avoids the memory bottleneck for large system sizes
                      and introduces even more parallel speedup. Calculations of
                      systems with up to 3584 atoms of Ge, Sb and Te were
                      performed on (up to) all 294,912 cores of JUGENE, the
                      massively parallel supercomputer installed at
                      Forschungszentrum Jülich.},
      cin          = {PGI-1 / IAS-1},
      cid          = {I:(DE-Juel1)PGI-1-20110106 / I:(DE-Juel1)IAS-1-20090406},
      pnm          = {422 - Spin-based and quantum information (POF2-422)},
      pid          = {G:(DE-HGF)POF2-422},
      typ          = {PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/128376},
}