Reactive Collisions and Final State Analysis in Hypersonic Flight Regime
Technical Report,15 Oct 2014,14 Oct 2015
Universitat Basel Basel Switzerland
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Classical molecular dynamics simulations of the nonreactive collision between the N 2 cation and Ar atoms at two different temperatures show that inelastic rotational excitation of the ion in the product channel is important and occurs more frequently than previously assumed. The simulations use an RKHS PES based on UCCSDTaug-cc-pVTZ electronic structure calculations and correct handling of the asymptotics within the RKHS framework. Analysis of the results for j 6 using a strict filtering criterion of fracv 0001 and a figure-of-merit j 2 suggests that inelastic collisions occur in at least 17 of the cases, which is one order of magnitude larger than reported in earlier experiments 2 . Interestingly, the N2Ar complex does not need to be formed and stabilized for rotational excitation to occur. A sufficiently close encounter of the two collision partners is sufficient to mutually influence their flight paths and lead to rotational excitation. It should be pointed out that the PES used in this work was calculated using a single reference method. Electronic effects, which are not adequately captured using single-reference methods, might play a non-negligible role in the dissociative region of the PES. Consequently, further investigations should employ multireference methods such as MRCI to capture electronic effects which are, however, outside the scope of the present work. For a complete understanding of the rate of rotational excitation in the N 2-Arsystem, new experiments, which allow precise control of the exact quantum state of the collision partners and additional computational investigations at the quantum level are necessary.