We present the reaction energetics of the missile propellant UDMH oxidation with both hydroxyl radical and ozone via CCSD(T)/CBS quantum chemical calculations. We also present the results for hydrazine oxidation, as a point of comparison. We find the reaction mechanism is very sensitive to correlation treatment, giving drastically different results based on geometries arising from KS-DFT, MBPT(2), CCSD, and CCSD(T). For example, the CCSD(T)/CBS estimate of the barrier changes by 2 kcal/mol merely from changing between the CCSD and CCSD(T) optimized structures. The near-attack complex is most affected by the correlation treatment and plays a significant role in determining the rate-limiting barrier. Ozonolysis of the species demonstrates somewhat late transition states, unsurprisingly requiring a triples treatment for accurate representation. CAS treatments suggest there to be no multi-reference nature to the wavefunction to explain these observations.

Quantum chemistry mechanism of UDMH/Hydrazine oxidation by radicals, ozone

ACS Spring 2022

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