Electron Paramagnetic Resonance A-tensor

Documentation on the molecular calculation of electron paramagnetic resonance (EPR) hyperfine coupling constants (A-tensors) using relativistic Kramers-unrestricted density functional theory. In the current version of ReSpect, the methodology can be combined with the 4C Hamiltonian.

Feature List

Wave function models

  • Kramers unrestricted Hartree-Fock or Kohn-Sham determinant for open-shell doublets and triplets


  • relativistic four-component (4c) Dirac-Coulomb

DFT non-collinear functionals

  • local (SVWN5)
  • GGA (PBE,BLYP,KT2,BP86,PP86)
  • hybrid (PBE0,B3LYP)
  • range-separated (LC-SVWN5,LC-BLYP,CAM-B3LYP)

Nuclear magnetic moment distribution models

  • point
  • finite Gaussian-type

Additional features

  • molecular orbital analysis
  • parallel execution on shared-memory parallel architectures (SMPs)

Related Publications

E. Malkin, M. Repisky, S. Komorovsky, P. Mach, O. L. Malkina, and V. G. Malkin
Effects of finite size nuclei in relativistic four-component calculations of hyperfine structure
J. Chem. Phys. 134, 044111 (2011)

S. Gohr, P. Hrobarik, M. Repisky, S. Komorovsky, K. Ruud, and M. Kaupp
Four-component relativistic density functional theory calculations of EPR g- and hyperfine-coupling tensors using hybrid functionals: validation on transition-metal complexes with large tensor anisotropies and higher-order spin-orbit effects
J. Phys. Chem. A 119, 12892–12905 (2015)

R. D. Remigio, M. Repisky, S. Komorovsky, P. Hrobarik, L. Frediani, and K. Ruud
Four-component relativistic density functional theory with the polarisable continuum model: application to EPR parameters and paramagnetic NMR shifts
Mol. Phys. 115, 214–227 (2017)

Book Chapter

S. Komorovsky
Relativistic Theory of EPR and (p)NMR
In: Yanez, Manuel and Boyd, Russell J. (eds.) Comprehensive Computational Chemistry, Vol. 3, Elsevier , 280–314 (2024)

Program Reference

M. Repisky, S. Komorovsky, M. Kadek, L. Konecny, U. Ekstrom, E. Malkin,
M. Kaupp, K. Ruud, O. L. Malkina, and V. G. Malkin
ReSpect: Relativistic spectroscopy DFT program package
J. Chem. Phys. 152, 184101 (2020)

Additional contributions from
R. Bast (AutoCMake), R. Di Remigio (PCMSolver), I. Malkin-Ondik (DKH2), and S. Knecht (MPI parallelization)

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Useful Links

Our Contacts

Hylleraas Centre
Department of Chemistry
UiT The Arctic University of Norway
Tromsø, NO-9037 Norway
Email: info@respectprogram.eu