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@ARTICLE{Lischka:889774,
      author       = {Lischka, Hans and Shepard, Ron and Müller, Thomas and
                      Szalay, Péter G. and Pitzer, Russell M. and Aquino, Adelia
                      J. A. and Araújo do Nascimento, Mayzza M. and Barbatti,
                      Mario and Belcher, Lachlan T. and Blaudeau, Jean-Philippe
                      and Borges, Itamar and Brozell, Scott R. and Carter, Emily
                      A. and Das, Anita and Gidofalvi, Gergely and González,
                      Leticia and Hase, William L. and Kedziora, Gary and Kertesz,
                      Miklos and Kossoski, Fábris and Machado, Francisco B. C.
                      and Matsika, Spiridoula and do Monte, Silmar A. and
                      Nachtigallová, Dana and Nieman, Reed and Oppel, Markus and
                      Parish, Carol A. and Plasser, Felix and Spada, Rene F. K.
                      and Stahlberg, Eric A. and Ventura, Elizete and Yarkony,
                      David R. and Zhang, Zhiyong},
      title        = {{T}he generality of the {GUGA} {MRCI} approach in
                      {COLUMBUS} for treating complex quantum chemistry},
      journal      = {The journal of chemical physics},
      volume       = {152},
      number       = {13},
      issn         = {1089-7690},
      address      = {Melville, NY},
      publisher    = {American Institute of Physics},
      reportid     = {FZJ-2021-00387},
      pages        = {134110 -},
      year         = {2020},
      abstract     = {The core part of the program system COLUMBUS allows highly
                      efficient calculations using variational multireference (MR)
                      methods in the framework of configuration interaction with
                      single and double excitations (MR-CISD) and averaged
                      quadratic coupled-cluster calculations (MR-AQCC), based on
                      uncontracted sets of configurations and the graphical
                      unitary group approach (GUGA). The availability of analytic
                      MR-CISD and MR-AQCC energy gradients and analytic
                      nonadiabatic couplings for MR-CISD enables exciting
                      applications including, e.g., investigations of
                      π-conjugated biradicaloid compounds, calculations of
                      multitudes of excited states, development of diabatization
                      procedures, and furnishing the electronic structure
                      information for on-the-fly surface nonadiabatic dynamics.
                      With fully variational uncontracted spin-orbit MRCI,
                      COLUMBUS provides a unique possibility of performing
                      high-level calculations on compounds containing heavy atoms
                      up to lanthanides and actinides. Crucial for carrying out
                      all of these calculations effectively is the availability of
                      an efficient parallel code for the CI step. Configuration
                      spaces of several billion in size now can be treated quite
                      routinely on standard parallel computer clusters. Emerging
                      developments in COLUMBUS, including the all configuration
                      mean energy multiconfiguration self-consistent field method
                      and the graphically contracted function method, promise to
                      allow practically unlimited configuration space dimensions.
                      Spin density based on the GUGA approach, analytic spin-orbit
                      energy gradients, possibilities for local electron
                      correlation MR calculations, development of general
                      interfaces for nonadiabatic dynamics, and MRCI linear
                      vibronic coupling models conclude this overview.},
      cin          = {JSC},
      ddc          = {530},
      cid          = {I:(DE-Juel1)JSC-20090406},
      pnm          = {511 - Computational Science and Mathematical Methods
                      (POF3-511)},
      pid          = {G:(DE-HGF)POF3-511},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {32268762},
      UT           = {WOS:000524553600002},
      doi          = {10.1063/1.5144267},
      url          = {https://juser.fz-juelich.de/record/889774},
}