Accession Number : AD1021185


Title :   Reactive Collisions and Final State Analysis in Hypersonic Flight Regime


Descriptive Note : Technical Report,15 Oct 2014,14 Oct 2015


Corporate Author : Universitat Basel Basel Switzerland


Personal Author(s) : Meuwly,Markus


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/1021185.pdf


Report Date : 13 Sep 2016


Pagination or Media Count : 43


Abstract : 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 UCCSD(T)/aug-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 frac(v') = 0:001 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.


Descriptors :   molecular dynamics simulations , energy transfer , arrhenius equation , chemical reaction properties , experimental data , high temperature , low temperature , angular momentum , electronic states , exchange reactions , first principles calculations , hypersonic flight


Distribution Statement : APPROVED FOR PUBLIC RELEASE