Journal article

NESSi : The Non-Equilibrium Systems Simulation package

  • Schüler, Michael Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland - Stanford Institute for Materials and Energy Sciences, SLAC & Stanford University, Stanford, CA 94025, USA
  • Golež, Denis Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland - Center for Computational Quantum Physics, Flatiron Institute, 162 Fifth avenue, New York, NY 10010, USA
  • Murakami, Yuta Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland - Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
  • Bittner, Nikolaj Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
  • Herrmann, Andreas Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
  • Strand, Hugo U. R. Center for Computational Quantum Physics, Flatiron Institute, 162 Fifth avenue, New York, NY 10010, USA - Department of Physics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
  • Werner, Philipp Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
  • Eckstein, Martin Department of Physics, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
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    01.12.2020
Published in:
  • Computer Physics Communications. - 2020, vol. 257, no. 2020, p. 107484
English The nonequilibrium dynamics of correlated many-particle systems is of interest in connection with pump–probe experiments on molecular systems and solids, as well as theoretical investigations of transport properties and relaxation processes. Nonequilibrium Green’s functions are a powerful tool to study interaction effects in quantum many-particle systems out of equilibrium, and to extract physically relevant information for the interpretation of experiments. We present the open-source software package NESSi (The Non-Equilibrium Systems Simulation package) which allows to perform many-body dynamics simulations based on Green’s functions on the L-shaped Kadanoff–Baym contour. NESSi contains the library libcntr which implements tools for basic operations on these nonequilibrium Green’s functions, for constructing Feynman diagrams, and for the solution of integral and integro-differential equations involving contour Green’s functions. The library employs a discretization of the Kadanoff–Baym contour into time N points and a high-order implementation of integration routines. The total integrated error scales up to O(N−7), which is important since the numerical effort increases at least cubically with the simulation time. A distributed-memory parallelization over reciprocal space allows large-scale simulations of lattice systems. We provide a collection of example programs ranging from dynamics in simple two-level systems to problems relevant in contemporary condensed matter physics, including Hubbard clusters and Hubbard or Holstein lattice models. The libcntr library is the basis of a follow-up software package for nonequilibrium dynamical mean-field theory calculations based on strong-coupling perturbative impurity solvers.Program summaryProgram Title: NESSi CPC Library link to program files: http://dx.doi.org/10.17632/973crf9hgd.1 Licensing provisions: MPL v2.0 Programming language: C++, python External routines/libraries: cmake, eigen3, hdf5 (optional), mpi (optional), omp (optional) Nature of problem: Solves equations of motion of time-dependent Green’s functions on the Kadanoff–Baym contour. Solution method: Higher-order solution methods of integral and integro-differential equations on the Kadanoff–Baym contour.
Faculty
Faculté des sciences et de médecine
Department
Département de Physique
Language
  • English
Classification
Physics
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/308930
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