Xray Absorption Spectroscopy with DR-TDDFT

Documentation on the molecular calculation of excitation energies and Xray electronic absorption spectra (XEAS) using relativistic damped-response time-dependent density functional theory (DR-TDDFT). In the current version of ReSpect, the methodology can be combined with the 1C, (e)amfX2C or 4C Hamiltonian and applied to closed-shell molecular systems.

Feature List

Wave function models

  • Kramers restricted Hartree-Fock or Kohn-Sham determinant for closed-shell singlets

Hamiltonians

  • non-relativistic one-component (1c)
  • relativistic four-component (4c) Dirac-Coulomb
  • relativistic two-component (2c) involving 1eX2C, amfX2C, eamfX2C or mmfX2C Hamiltonian models
  • scalable speed of light
  • switchable spin-orbit interaction

DFT non-collinear functionals

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

DFT non-collinear analytical kernels

  • full expressions including the GGA part
  • adiabatic local density approximation (ALDA/XALDA)

Integral evaluation techniques

  • analytic with an in-built restricted kinetic balanced (RKB) condition for the small-component
  • one-center approximation for the SSSS-type electron repulsion integrals

Additional features

  • Tamm–Dancoff approximation (TDA)
  • core-valence separation (CVS)
  • restart from a previous run
  • molecular orbital analysis
  • parallel execution on shared-memory parallel architectures (SMPs)

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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Our Contacts

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