Potential Energy Surfaces (PES) are used to study elementary state to state reactions and their dynamics, but in a complex reactive system many elementary reactions are involved and the overall study becomes difficult. MreaDy program (Multi-process Reactions Dynamics), aims to reproduce such complex mechanisms, by defining a global Potential Energy Surface (gPES) for the process in question. It integrates various PESs representing the elementary reaction present in the chemical process, and performs reactive classical dynamic calculations on it. We have followed the evolution of the hydroxyl radical in its ground electronic state, OH (2Π), in a combustion of a equimolecular mixture of oxygen and hydrogen, at 1000, 2000 and 3000 K, during the first ns of the reaction. Preliminary results show that collisions are more efficient in rotational and translational energy transfer than in vibrational quenching, leading to a OH radical vibrationally excited. MReaDy was modified to study also the pressure dependence of the reaction H + O2 + M -&gt; HO2 + M, one of the main sources of uncertainty when modeling hydrogen combustion chemistry. It is a termolecular reaction, therefore it cannot be studied using normal classical trajectory programs. Excited HO2* radicals are formed due to hydrogen and oxygen collisions. We then determine how fast the excited HO2* radicals are created and stabilized to HO2 by collisions at different pressures and temperatures, leading to the determination of the rate constant as a function of pressure. Intermediate reactions present in the system are also characterized.

Combustion dynamics and kinetics from potential energy surfaces: The MReaDy approach

256th National Meeting (2018)

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