Theoretical Chemistry Accounts

, Volume 127, Issue 3, pp 211–221

Orbital relaxation and the third-order induction energy in symmetry-adapted perturbation theory

  • Konrad Patkowski
  • Krzysztof Szalewicz
  • Bogumil Jeziorski
Regular Article

DOI: 10.1007/s00214-010-0748-0

Cite this article as:
Patkowski, K., Szalewicz, K. & Jeziorski, B. Theor Chem Acc (2010) 127: 211. doi:10.1007/s00214-010-0748-0

Abstract

Theoretical investigations of the induction interaction between closed-shell molecules which fully account for the orbital relaxation effects are presented. Explicit expressions for the third-order induction energy in terms of molecular integrals and orbital energies are given and implemented within the sapt2008 program for symmetry-adapted perturbation theory (SAPT) calculations. Numerical investigations for the He–He, He–LiH, Ar–Ar, H2–CO, H2O–H2O, and H2O–NH3 model dimers show that the orbital relaxation increases the third-order induction interaction by 15 to 50% at near-equilibrium geometries, with the largest effect observed for complexes involving highly polar monomers. At large intermonomer separations, the relaxed third-order induction energy perfectly recovers the difference \(\delta E^{\rm HF}_{\rm int}\) between the Hartree–Fock interaction energy and the sum of the uncorrelated SAPT contributions through second order in the intermolecular interaction operator. At the near-equilibrium geometries, the sum of the relaxed third-order induction and exchange-induction energies reproduces, however, only a small fraction (6 to 15%) of \(\delta E^{\rm HF}_{\rm int}\) for the nonpolar systems and about 40 to 60% for the polar ones. A comparison of the complete SAPT calculations with the coupled-cluster treatment with single, double, and noniterative triple excitations [CCSD(T)] suggests that the pure SAPT approach with all the available third-order corrections is more accurate for nonpolar systems while for the polar ones the hybrid approach including \(\delta E^{\rm HF}_{\rm int}\) gives better results.

Keywords

Intermolecular interactionsSymmetry-adapted perturbation theoryInduction energy

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Konrad Patkowski
    • 1
  • Krzysztof Szalewicz
    • 1
  • Bogumil Jeziorski
    • 2
  1. 1.Department of Physics and AstronomyUniversity of DelawareNewarkUSA
  2. 2.Faculty of ChemistryUniversity of WarsawWarsawPoland