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What Is the Accuracy Limit of Adiabatic Linear-Response TDDFT Using Exact Exchange-Correlation Potentials and

Jaspreet Kaur1, Egor Ospadov1, Viktor N Staroverov1

  • 1Department of Chemistry , The University of Western Ontario , London , Ontario N6A 5B7 , Canada.

Journal of Chemical Theory and Computation
|August 7, 2019
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Summary
This summary is machine-generated.

Improving Kohn-Sham potentials in time-dependent density-functional theory (TDDFT) significantly enhances accuracy for calculating excitation energies. This study reveals a practical accuracy limit for TDDFT by optimizing potentials alone.

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Area of Science:

  • Computational chemistry
  • Quantum mechanics
  • Electronic structure theory

Background:

  • Time-dependent density-functional theory (TDDFT) is a method for calculating vertical excitation energies.
  • Standard density-functional approximations (DFAs) yield mean absolute errors (MAEs) from 0.2 eV to over 1 eV for TDDFT calculations.
  • The accuracy of TDDFT is influenced by the quality of Kohn-Sham potentials and exchange-correlation kernels.

Purpose of the Study:

  • To investigate the impact of increasingly accurate exchange-correlation potentials on TDDFT performance.
  • To determine the practical accuracy limit of TDDFT achievable by improving Kohn-Sham potentials.

Main Methods:

  • Adiabatic linear-response TDDFT framework.
  • Utilized static Kohn-Sham potentials derived from Hartree-Fock (HF) and post-HF wavefunctions.
  • Employed various approximate exchange-correlation kernels.

Main Results:

  • Lowest MAEs for valence excitations reached 0.15-0.2 eV when using accurate potentials.
  • This accuracy level suggests a practical limit for TDDFT improvements solely through potential optimization.
  • Findings confirm and extend previous observations on the importance of accurate potentials.

Conclusions:

  • Improving Kohn-Sham potentials is crucial for enhancing TDDFT accuracy in excitation energy calculations.
  • The study establishes a benchmark for TDDFT accuracy, highlighting the role of potential quality.
  • Further advancements may require improvements beyond solely refining potentials.