Equilibrium Geometry of the Ethynyl (CCH) Radical

P. Szalay, Lea S. Thøgersen, Jeppe Olsen, M. Kállay, Jürgen Gauss

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Abstract

The equilibrium geometry of the ethynyl (CCH) radical has been obtained using the results of high-level quantum chemical calculations and the available experimental data. In a purely quantum chemical approach, the best theoretical estimates (1.208 Å for rCC and 1.061-1.063 Å for r CH) have been obtained from CCSD(T), CCSDT, MR-AQCC, and full CI calculations with basis sets up to core-polarized pentuple-zeta quality. In a mixed theoretical-experimental approach, empirical equilibrium geometrical parameters (1.207 Å for rCC and 1.069 Å for r CH) have been obtained from a least-squares fit to the experimental rotational constants of four isotopomers of CCH which have been corrected for vibrational effects using computed vibration-interaction constants. These geometrical parameters lead to a consistent picture with remaining discrepancies between theory and experiment of 0.001 Å for the CC and 0.006-0.008 Å for the CH distances, respectively. The corresponding rs and r0 geometries are shown not to be representative for the true equilibrium structure of CCH.

Original languageEnglish
Pages (from-to)3030-3034
Number of pages5
JournalJournal of Physical Chemistry A
Volume108
Issue number15
DOIs
Publication statusPublished - Apr 15 2004

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methylidyne
Geometry
geometry
vibration
Experiments
estimates
interactions

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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Equilibrium Geometry of the Ethynyl (CCH) Radical. / Szalay, P.; Thøgersen, Lea S.; Olsen, Jeppe; Kállay, M.; Gauss, Jürgen.

In: Journal of Physical Chemistry A, Vol. 108, No. 15, 15.04.2004, p. 3030-3034.

Research output: Contribution to journalArticle

Szalay, P. ; Thøgersen, Lea S. ; Olsen, Jeppe ; Kállay, M. ; Gauss, Jürgen. / Equilibrium Geometry of the Ethynyl (CCH) Radical. In: Journal of Physical Chemistry A. 2004 ; Vol. 108, No. 15. pp. 3030-3034.
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