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Theoretical Chemistry Accounts

, Volume 105, Issue 1, pp 7–14 | Cite as

The inclusion of electron correlation in intermolecular potentials: applications to the formamide dimer and liquid formamide

  • Steve Brdarski
  • Per-Olof Åstrand
  • Gunnar Karlström
Regular article

Abstract.

A test of the quality of the electrostatic properties and polarizabilities used in the nonempirical molecular orbital (NEMO) potential is carried out for formamide by calculating the molecular dipole moment and polarizability at the second-order Møller–Plesset (MP2) level of theory. The molecular dipole moment is 11% lower at the MP2 level than at the Hartree–Fock (HF) level, whereas the isotropic part of the polarizability is increased by 36% by adding electron correlation and using a considerably larger basis set. The atomic charges, dipole moments and polarizabilities obtained at the HF level are rescaled to get the correct molecular properties at the MP2 level. The potential minimum for the cyclic dimer of formamide is −17.50 kcal/mol with the MP2-scaled properties and is significantly lower than other potentials give. Two intermolecular potentials are constructed and used in subsequent molecular dynamics simulations: one with the regular NEMO potential and the other with the rescaled MP2 properties. A damping of the electrostatic field at short intermolecular distances is included in the present NEMO model. The average energies for liquid formamide are lower for the MP2-scaled model and are in good agreement with experimental results. The lowering of the simulation energy for the MP2-scaled potential indicates the strong dispersive interactions in liquid formamide.

Key words: Dispersion interaction – Hydrogen bonds – Molecular dynamics – Polarizable potentials 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • Steve Brdarski
    • 1
  • Per-Olof Åstrand
    • 2
  • Gunnar Karlström
    • 1
  1. 1. Department of Theoretical Chemistry, Center for Chemistry and Chemical Engineering, University of Lund, P.O. Box 124, 22100 Lund, SwedenSE
  2. 2. Condensed Matter Physics and Chemistry Department, Riso National Laboratory, P.O. Box 49, 4000 Roskilde, DenmarkDK

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