Molecular Conformations and Relative Stabilities Can Be as Demanding of Electronic Structure Method as Intermolecular Calculations

Tanja Van Mourik, Panagiotis G. Karamertzanis, Sarah L. Price

Research output: Contribution to journalArticlepeer-review

116 Citations (Scopus)

Abstract

We have performed a variety of high-level electronic structure calculations on two moderately sized organic molecules and found considerable sensitivity of the intramolecular potential energy surface to the method employed. The gas-phase structure of tyrosine-glycine varies qualitatively between B3LYP and MP2 optimizations, producing different close contacts between the tyrosine ring and the glycine moiety. The relative energies of the 2-(acetylamino)benzamide conformations found in its two polymorphs can vary by over 20 kJ mol(-1) between MP2 and B3LYP calculations, using the same basis set. It is shown by a novel analysis that the intramolecular equivalent of basis set superposition error competes with the errors in the intramolecular dispersion in causing this sensitivity.

Original languageEnglish
Pages (from-to)8-12
Number of pages5
JournalJournal of Physical Chemistry A
Volume110
Issue number1
DOIs
Publication statusPublished - 12 Jan 2006

Keywords

  • DENSITY-FUNCTIONAL THEORY
  • VAN-DER-WAALS
  • CRYSTAL-STRUCTURE PREDICTION
  • PLESSET PERTURBATION-THEORY
  • AB-INITIO
  • MOLLER-PLESSET
  • BINDING-ENERGIES
  • LOCAL MP2
  • DFT
  • SYSTEMS

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