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Third-order corrections to random-phase approximation correlation energies.

Andreas Hesselmann1

  • 1Lehrstuhl für Theoretische Chemie, Universität Erlangen-Nürnberg, Egerlandstr. 3, D-91058 Erlangen, Germany. andreas.hesselmann@chemie.uni-erlangen.de

The Journal of Chemical Physics
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Several random-phase approximation (RPA) correlation methods were improved for accuracy in third-order perturbation theory. A new correction method enhances RPA

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Area of Science:

  • Quantum Chemistry
  • Computational Chemistry
  • Theoretical Chemistry

Background:

  • Random-phase approximation (RPA) methods are widely used for calculating correlation energies in electronic structure theory.
  • Existing RPA methods exhibit inaccuracies in third-order perturbation theory due to missing particle-particle-hole-hole interactions.

Purpose of the Study:

  • To evaluate and improve the accuracy of various RPA correlation methods in third-order perturbation theory.
  • To develop a correction method that makes RPA approaches exact to third order.

Main Methods:

  • Comparison of several RPA correlation methods at third-order perturbation theory.
  • Derivation of a simple correction method to account for missing interactions.
  • Validation using reaction energies for 21 organic molecules and interaction energies for 23 molecular complexes.

Main Results:

  • Third-order correlation energy contributions significantly differ among RPA methods.
  • The derived correction method successfully makes RPA methods exact to third-order perturbation theory.
  • The corrected RPA methods show considerably improved accuracy compared to coupled-cluster singles doubles with perturbative triples (CCSD(T)).

Conclusions:

  • The proposed correction method enhances the accuracy of RPA correlation methods.
  • This advancement provides a more reliable and computationally efficient approach for studying chemical reactions and intermolecular interactions.