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Replacing the Görling-Levy component in double hybrid functionals with direct random phase approximation (dRPA) improves accuracy for systems with static correlation. This enhanced approach shows competitive performance and offers computational advantages.

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Area of Science:

  • Computational Chemistry
  • Quantum Chemistry
  • Theoretical Chemistry

Background:

  • The Görling-Levy second-order perturbation theory (PT2) component in double hybrid density functional theory (DHDFT) struggles with systems exhibiting significant static correlation.
  • This limitation hinders the accuracy of DHDFT for certain challenging chemical systems.

Purpose of the Study:

  • To investigate the replacement of the PT2 component with the direct random phase approximation (dRPA) in double hybrid functionals.
  • To evaluate the performance of the modified functionals with empirical dispersion corrections and semilocal correlation components.
  • To explore an alternative MP3-like correction for further performance enhancement.

Main Methods:

  • Exploration of replacing the PT2 component with dRPA, inspired by the SCS-dRPA75 functional.
  • Addition of D4 empirical dispersion correction and semilocal correlation components.
  • Investigation of an MP3-like correction term added to a range-separated double hybrid functional.
  • Assessment using the GMTKN55 benchmark suite and evaluation of basis set sensitivity.

Main Results:

  • The DSD-PBEdRPA75-D4 functional demonstrated significant improvements, approaching the performance of established high-accuracy functionals like revDSD-PBEP86-D4 and Berkeley ωB97M(2).
  • The dRPA-based approach showed reduced sensitivity to the choice of semilocal functional but increased basis set sensitivity compared to PT2-based methods.
  • An alternative MP3-like correction yielded a lower weighted mean absolute deviation (WTMAD2) on the GMTKN55 benchmark suite.
  • Computational cost of the MP3-like correction can be managed using density fitting techniques.

Conclusions:

  • Replacing the PT2 component with dRPA offers a viable strategy to improve double hybrid functional performance, particularly for systems with static correlation.
  • The developed DSD-PBEdRPA75-D4 functional represents a promising advancement in accuracy for thermochemistry.
  • The MP3-like correction provides an effective alternative for enhancing accuracy, with manageable computational overhead.