Reactive collisions for NO(²Π) + N(⁴S) at temperatures relevant to the hypersonic flight regime

Abstract

The NO(XΠ) + N(S) reaction which occurs entirely in the triplet manifold of NO is investigated using quasiclassical trajectories and quantum simulations. Fully-dimensional potential energy surfaces for the A' andA'' states are computed at the MRCI+Q level of theory and are represented using a reproducing kernel Hilbert space. The N-exchange and N-formation channels are followed by using the multi-state adiabatic reactive molecular dynamics method. Up to 5000 K these reactions occur predominantly on the NO A'' surface. However, for higher temperatures the contributions of theA' and A'' states are comparable and the final state distributions are far from thermal equilibrium. From the trajectory simulations a new set of thermal rate coefficients of up to 20 000 K is determined. Comparison of the quasiclassical trajectory and quantum simulations shows that a classical description is a good approximation as determined from the final state analysis.

Reactive atomistic simulations of Diels-Alder reactions: The importance of molecular rotations

“…Gas-phase reactive molecular dynamics simulations starting from an equilibrated ensemble of a statistically significant number of initial conditions, on the other hand, have recently been shown to provide molecular-level details into reactions relevant to atmospheric chemistry 28,29 and reactions in the hypersonic regime. 30,31 From an experimental perspective, the most precise data on reaction mechanisms and dynamics can be gained from gas-phase studies performed under single-collision conditions. As the progress in molecular-beam experiments allows the probing of ever-larger systems under precisely defined conditions, 32,33 the open questions pertaining to the mechanistic details of Diels-Alder reactions become an attractive target of study.…”

Multistate Reactive Molecular Dynamics Simulations of Proton Diffusion in Water Clusters and in the Bulk

“…In Eq. 10, w j (x) is the normalized weight 35,42 which has also been used for mixing double many-body expansion PESs. 43 However, other mixing functions are possible such as a tangent hyperbolic 34,41 and thus, no physical significance should be attributed to the mixing function.…”

Reactive molecular dynamics: From small molecules to proteins

“…This work focused on the scattering process and found that the fraction of NO deflected in the forward direction decreases with increasing collision energy. Complementary to this, RKHS‐interpolated PESs based on MRCI+Q calculations were used to determine rate coefficients for different reaction channels for temperatures up to 20,000 K (see Figure ; Reference ). From the QCT simulations the rates k ( T ) for 5,000 ≤ T ≤ 20,000 can be fit to an Arrhenius expression and for the exchange and N 2 formation processes, respectively.…”

“…For the related NO(X 2 Π) + N( 4 S) $ N 2 (X 1 Σ) + O( 3 P) reaction fully dimensional, global PESs have also been computed. [161][162][163] Based on CASPT2 calculations a many-body expansion was fitted and used for variational transition state calculations 162 and QCT simulations. 164 A more recent effort used a least-squares fit of permutationally invariant polynomials to dynamically scaled MRCI energies.…”