Anharmonic force fields of cis- and trans-S1 C2H 2

J. H. Baraban, J. F. Stanton, A. J. Merer, R. W. Field

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


We calculate second-order vibrational perturbation theory (VPT2) anharmonic force fields for the cis and trans conformers of S1 C 2H2, and compare the results to experiment. The vibrational assignments of recently observed levels belonging to the cis well are of particular interest. A refined estimate of the cis origin position (44,870±10 cm-1) is proposed, and preliminary low-energy fits to the global J=K=0 trans level structure are also described. The performance of perturbation theory in this isomerizing system is examined, and both surprising successes and failures are encountered. We examine these and their causes, and offer practical suggestions for avoiding the pitfalls of applying perturbation theory to systems with large amplitude motions.

Original languageEnglish
Pages (from-to)2725-2733
Number of pages9
JournalMolecular Physics
Issue number21-22
StatePublished - 1 Nov 2012
Externally publishedYes


  • Acetylene
  • Anharmonic force fields
  • Cis-trans isomerization
  • Spectroscopy
  • Vibrational perturbation theory

ASJC Scopus subject areas

  • Biophysics
  • Molecular Biology
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry


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