• Electron-photon exchange-correlation approximation for quantum-electrodynamical density-functional theory 

      Lu, I-Te; Ruggenthaler, Michael; Tancogne-Dejean, Nicolas; Latini, Simone; Penz, Markus; Rubio, Angel (Peer reviewed; Journal article, 2024)
      Quantum-electrodynamical density-functional theory (QEDFT) provides a promising avenue for exploring complex light-matter interactions in optical cavities for real materials. Similar to conventional densityfunctional theory, ...
    • Exchange energies with forces in density-functional theory 

      Tancogne-Dejean, Nicolas; Penz, Markus; Laestadius, Andre; Csirik, Mihaly Andras; Ruggenthaler, Michael; Rubio, Angel (Peer reviewed; Journal article, 2024)
      We propose exchanging the energy functionals in ground-state density-functional theory with physically equivalent exact force expressions as a new promising route toward approximations to the exchange–correlation potential ...
    • Exchange-only virial relation from the adiabatic connection 

      Laestadius, Andre; Csirik, Mihaly Andras; Penz, Markus; Tancogne-Dejean, Nicolas; Ruggenthaler, Michael; Rubio, Angel; Helgaker, Trygve (Peer reviewed; Journal article, 2024)
      The exchange-only virial relation due to Levy and Perdew is revisited. Invoking the adiabatic connection, we introduce the exchange energy in terms of the right-derivative of the universal density functional w.r.t. the ...
    • Quantum-Electrodynamical Density-Functional Theory Exemplified by the Quantum Rabi Model 

      Bakkestuen, Vebjørn Hallberg; Falmår, Vegard; Lotfigolian, Maryam; Penz, Markus; Ruggenthaler, Michael; Laestadius, Andre (arXiv.org;, Journal article, 2024)
      The key features of density-functional theory (DFT) within a minimal implementation of quantum lectrodynamics are demonstrated, thus allowing to study elementary properties of quantum-electrodynamical density-functional ...
    • Solution of the υ-representability problem on a one-dimensional torus 

      Sutter, Sarina M; Penz, Markus; Ruggenthaler, Michael; Leeuwen, Robert van; Giesbertz, Klaas J H (Journal of Physics A: Mathematical and Theoretical;, Peer reviewed; Journal article, 2024)
      We provide a solution to the v-representability problem for a non-relativistic quantum many-particle system on a onedimensional torus domain in terms of Sobolev spaces and their duals. Any one-particle density that is ...
    • The structure of the density-potential mapping Part I: Standard density-functional theory 

      Penz, Markus; Tellgren, Erik Ingemar; Csirik, Mihaly Andras; Ruggenthaler, Michael; Laestadius, Andre (Peer reviewed; Journal article, 2023)
    • The Structure of the Density-Potential Mapping. Part II: Including Magnetic Fields 

      Penz, Markus; Tellgren, Erik Ingemar; Csirik, Mihaly Andras; Ruggenthaler, Michael; Laestadius, Andre (Peer reviewed; Journal article, 2023)
      The Hohenberg−Kohn theorem of density-functional theory (DFT) is broadly considered the conceptual basis for a full characterization of an electronic system in its ground state by just one-body particle density. In this ...
    • The Structure of the Density-Potential Mapping. Part II: Including Magnetic Fields 

      Penz, Markus; Tellgren, Erik Ingemar; Csirik, Mihaly Andras; Ruggenthaler, Michael; Laestadius, Andre (Peer reviewed; Journal article, 2023)
      The Hohenberg−Kohn theorem of density-functional theory (DFT) is broadly considered the conceptual basis for a full characterization of an electronic system in its ground state by just one-body particle density. In this ...