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@ARTICLE{Czaja:851556,
      author       = {Czaja, Philippe and Celino, Massimo and Giusepponi, Simone
                      and Gusso, Michele and Aeberhard, Urs},
      title        = {{A}b initio study on localization and finite size effects
                      in the structural, electronic, and optical properties of
                      hydrogenated amorphous silicon},
      journal      = {Computational materials science},
      volume       = {155},
      issn         = {0927-0256},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier Science},
      reportid     = {FZJ-2018-05181},
      pages        = {159 - 168},
      year         = {2018},
      abstract     = {We present a first-principles study of the structural,
                      electronic, and optical properties of hydrogenated amorphous
                      silicon (a-Si:H). To this end, atomic configurations of
                      a-Si:H with 72 and 576 atoms respectively are generated
                      using ab initio molecular dynamics, where the larger
                      structures are defect free, closely matching the
                      experimental situation and enabling the comparison of the
                      electronic and optical properties with experimental results.
                      Density functional theory calculations are applied to both
                      configurations in order to obtain the electronic wave
                      functions. These are analyzed and characterized with respect
                      to their localization and their contribution to the density
                      of states, and are used for calculating ab initio absorption
                      spectra of a-Si:H. The results show that both the size and
                      the defect structure of the configurations modify the
                      electronic and optical properties and in particular the
                      value of the band gap. This value could be improved by
                      calculating quasi-particle (QP) corrections to the
                      single-particle spectra using the G0W0 method. We find that
                      the QP corrections can be described by a set of scissors
                      shift parameters, which can also be used in calculations of
                      larger structures. The analysis of individual contributions
                      to the absorption by evaluating the optical matrix elements
                      indicates that strong localization enhances the optical
                      coupling, but has little effect on the average transition
                      probability , for which we find a dependence on the photon
                      energy E, irrespective of the nature of the initial or final
                      state.},
      cin          = {IEK-5 / JARA-HPC},
      ddc          = {530},
      cid          = {I:(DE-Juel1)IEK-5-20101013 / $I:(DE-82)080012_20140620$},
      pnm          = {121 - Solar cells of the next generation (POF3-121) /
                      Ab-initio description of charge carrier dynamics at
                      defective interfaces in solar cells $(jiek50_20171101)$},
      pid          = {G:(DE-HGF)POF3-121 / $G:(DE-Juel1)jiek50_20171101$},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000447748900019},
      doi          = {10.1016/j.commatsci.2018.08.027},
      url          = {https://juser.fz-juelich.de/record/851556},
}