Cold and ultracold NH-NH collisions: The field-free case
Cold and ultracold NH-NH collisions: The field-free case
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DOI：
10.1063/1.3570596
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发表时间：
2011-03-28
影响因子：
4.4
通讯作者：
Groenenboom, Gerrit C.
中科院分区：
文献类型：
--
作者：
Janssen, Liesbeth M. C.;Zuchowski, Piotr S.;Groenenboom, Gerrit C.
我们提出了冷和超冷 NH(X-3 Sigma(-)) + NH(X-3 Sigma(-)) 碰撞的弹性和非弹性自旋变化截面，这些截面是通过精确的从头算五重势能表面上的全量子散射计算获得的。尽管我们只考虑零场中的碰撞，但我们重点关注与磁捕获实验相关的横截面。结果表明，对于允许 s 波碰撞的超精细态，费米子 (NH)-N-14 和玻色子 (NH)-N-15 的蒸发冷却可能会成功。由于（准）束缚态共振的存在，计算的横截面对相互作用势的细节非常敏感。因此，从头算势能面的剩余不准确性导致了数值横截面值的不确定性。然而，根据从头计算的不确定性范围的采样，我们得出结论，确切的潜力可能是弹性与非弹性横截面之比足够大以实现有效的蒸发冷却。这种可能性仅微弱地依赖于散射计算中使用的通道基组的大小。 (C) 2011 年美国物理研究所。 [doi:10.1063/1.3570596]
We present elastic and inelastic spin-changing cross sections for cold and ultracold NH(X-3 Sigma(-)) + NH(X-3 Sigma(-)) 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 (NH)-N-14 and bosonic (NH)-N-15 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. (C) 2011 American Institute of Physics. [doi:10.1063/1.3570596]