Insufficient description of dispersion in B3LYP and large basis set superposition errors in MP2 calculations can hide peptide conformers

Leo F. Holroyd, Tanja Van Mourik

Research output: Contribution to journalArticlepeer-review

106 Citations (Scopus)

Abstract

B3LYP/6-31+G(d) and MP2/6-31+G(d) calculations predict markedly different structures for one Tyr-Gly conformer. Calculation of the energy profile for rotation around the glycine C-alpha-N bond reveals one minimum in the B3LYP profile (phi(gly) = 180 degrees) and two in the MP2 profile (similar to 75 degrees and 280 degrees). Large intramolecular BSSE values are responsible for masking the 180 degrees-minimum in the MP2 profile: approximate elimination of BSSE in the MP2 calculations - by (1) correction using BSSE values from complexes of phenol and N-formylglycine, (2) the application of local MP2, or (3) employing large basis sets (aug-cc-pVTZ/QZ) and density fitting - yields an unambiguous triple-well potential. (C) 2007 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)42-46
Number of pages5
JournalChemical Physics Letters
Volume442
Issue number1-3
DOIs
Publication statusPublished - 6 Jul 2007

Keywords

  • DENSITY-FUNCTIONAL-THEORY
  • PLESSET PERTURBATION-THEORY
  • QUANTUM-CHEMICAL CALCULATIONS
  • AB-INITIO
  • GLYCINE DIPEPTIDE
  • GAS-PHASE
  • COMPLEXES
  • ENERGIES
  • DFT
  • HYDROGEN

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