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Cold and ultracold NH-NH collisions : the field-free case

Janssen, Liesbeth M.C.; Zuchowski, Piotr S.; van der Avoird, Ad; Hutson, Jeremy M.; Groenenboom, Gerrit C.

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Liesbeth M.C. Janssen

Piotr S. Zuchowski

Ad van der Avoird

Gerrit C. Groenenboom


We present elastic and inelastic spin-changing cross sections for cold and ultracold NH(X 3Σ−) + NH(X 3Σ−) collisions, obtained from full quantum scattering calculations on an accurate ab initio quintet potential-energy surface. Although we consider only collisions in zero field, we focus on the cross sections relevant for magnetic trapping experiments. It is shown that evaporative cooling of both fermionic 14NH and bosonic 15NH is likely to be successful for hyperfine states that allow s-wave collisions. The calculated cross sections are very sensitive to the details of the interaction potential, due to the presence of (quasi)bound state resonances. The remaining inaccuracy of the ab initio potential-energy surface therefore gives rise to an uncertainty in the numerical cross-section values. However, based on a sampling of the uncertainty range of the ab initio calculations, we conclude that the exact potential is likely to be such that the elastic-to-inelastic cross-section ratio is sufficiently large to achieve efficient evaporative cooling. This likelihood is only weakly dependent on the size of the channel basis set used in the scattering calculations.


Janssen, L. M., Zuchowski, P. S., van der Avoird, A., Hutson, J. M., & Groenenboom, G. C. (2011). Cold and ultracold NH-NH collisions : the field-free case. The Journal of Chemical Physics, 134(12), Article 124309.

Journal Article Type Article
Publication Date Jan 1, 2011
Deposit Date Jun 19, 2013
Publicly Available Date Jun 27, 2013
Journal Journal of Chemical Physics
Print ISSN 0021-9606
Electronic ISSN 1089-7690
Publisher American Institute of Physics
Peer Reviewed Peer Reviewed
Volume 134
Issue 12
Article Number 124309


Published Journal Article (685 Kb)

Copyright Statement
© 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Janssen, Liesbeth M. C. and Zuchowski, Piotr S. and van der Avoird, Ad and Hutson, Jeremy M. and Groenenboom, Gerrit C. (2011) 'Cold and ultracold NH-NH collisions : the field-free case.', Journal of chemical physics., 134 (12). p. 124309 and may be found at

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