Spectroscopic, collisional, and thermodynamic properties
of the He-CO2 complex from an ab initio SAPT potential
Tatiana Korona and Robert Moszynski
Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
Franck Thibault, Béatrice Bussery-Honvault, Joël Boissoles,
and Jean-Michel Launay
Equipe SIMPA, Laboratoire PALMS, Université de Rennes 1, 35042 Rennes, France
Paul E.S. Wormer
Institute of Theoretical Chemistry, University of Nijmegen, 6525ED Nijmegen, The Netherlands
Abstract
Symmetry-adapted perturbation theory has been applied to compute a
two-dimensional potential energy surface of the He-CO2 complex. The
interaction energy is found to be dominated by the first-order exchange energy
and the second-order dispersion contribution. The ab initio potential has a
single minimum for the T-shaped geometry of the complex. The computed
points have been analytically fitted and used in converged calculations of the
bound rovibrational states of the complex and of the infrared spectrum
corresponding to the simultaneous excitation of the 3 vibration and internal
rotation in the CO2 subunit. The predicted theoretical spectrum is in an
excellent agreement with the experimental data of D.J. Nesbitt and
collaborators. The theoretical potential was also checked by comparison of the
computed pressure broadening coefficients and second virial coefficients with
the experimental data. The ab initio collisional pressure broadening and
termodynamic virial data lie within the experimental error bars over a wide
range of temperatures.