Speaker
Description
To study the rate of elementary reactions and their dynamics, we use Potential Energy Surfaces, being useful to compute state-to-state rate constants. The usual approach to study such system is to make use of all the system's available rate constants and build a system of master equations. This procedure assumes that reactants are in thermal equilibrium. Studies seem to indicate that the number of non-reactive collisions can be small and the energy distribution of the intermediate species may be far from the Boltzmann distribution. MreaDy[1] program (Multi-process Reactions Dynamics), aims to reproduce complex mechanisms, such as the hydrogen combustion, using accurate PES. We have introduced modifications on this program in order to study the pressure dependence of the reaction H + O2 + M → HO2 + M. This reaction is one of the main sources of uncertainty when modelling hydrogen combustion chemistry, and being a termolecular reaction, it cannot be studied using normal classical trajectory programs. We start with hydrogen atoms and oxygen molecules, forming by collision excited HO2 radicals. We can count how many of the excited HO2 radicals are stabilized by collisions at 1500, 2000, and 2500 K and pressures of 10, 20, 30 and 50 atm., and we calculate the formation rate of stable HO2 radicals. We present preliminary results for this process showing a clear increase of the rate constant with pressure. We are also able to study the rate constants of the different reactions present in the system.
