EDP Sciences
Free access
Issue
A&A
Volume 446, Number 1, January IV 2006
Page(s) 367 - 372
Section Atomic, molecular and nuclear data
DOI http://dx.doi.org/10.1051/0004-6361:20053919


A&A 446, 367-372 (2006)
DOI: 10.1051/0004-6361:20053919

Improved low-temperature rate constants for rotational excitation of CO by H $_\mathsf{2}$

M. Wernli1, P. Valiron1, A. Faure1, L. Wiesenfeld1, P. Jankowski2 and K. Szalewicz3

1  Laboratoire d'Astrophysique de Grenoble, UMR 5571 CNRS-UJF, OSUG, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France
    e-mail: michael.wernli@obs.ujf-grenoble.fr
2  Department of Quantum Chemistry, Institute of Chemistry, Nicholaus Copernicus University, Gagarina 7, 87-100 Torun, Poland
3  Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA

(Received 26 July 2005 / Accepted 12 September 2005)

Abstract
Cross sections for the rotational (de)excitation of CO by ground state para- and ortho-H2 are obtained using quantum scattering calculations for collision energies between 1 and 520 cm-1. A new CO-H2 potential energy surface is employed and its quality is assessed by comparison with explicitly correlated CCSD(T)-R12 calculations. Rate constants for rotational levels of CO up to 5 and temperatures in the range 5-70 K are deduced. The new potential is found to have a strong influence on the resonance structure of the cross sections at very low collision energies. As a result, the present rates at 10 K differ by up to 50% with those obtained by Flower (2001) on a previous, less accurate, potential energy surface.


Key words: molecular data - molecular processes - ISM: molecules




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