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The collision of OH with the oxygen molecule is studied by the trajectory simulation technique on the model potential energy surface of OH + 0 2 -0 3 + H chemical reaction. Although the reaction channel is closed, we aim to demonstrate that the L-shape of the OH + 0 2 valley leads to the effective coupling of OH(v) vibration with the relative motion of collisional partners and therefore explains the high value of the vibrational relaxation rate constant observed experimentally. The characteristic feature of the mechanism considered is the predominance of one-quantum relaxation for low and multiquantum transitions for high OH vibrational levels. To estimate state-to-state vibrational relaxation rate constants, the method of dynamical corrections of transition state theory is used. The expression for the rate constant consists of a transition state term and a correction factor, determined in two-dimensional classical trajectory calculations. We also demonstrate the instability of motion on the potential energy surface with the L-shape valley, resulting from the scattering of the trajectory on the "comer" of the potential energy surface and the presence of regular and chaotic motions.

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Present-day computational techniques provide a possibility of evaluating properties of macrosystems using ab initio quantum chemistry and theories of elementary processes. Physical and chemical phenomena on very different timescales have to be taken into account (excitation, emission, chemical reactions, diffusion) at different levels of refining. This refining covers a very wide region of parameters starting from the structure of species up to the macro chemical mechanism of their conversion. This multilevel approach is described in detail in the paper and includes interaction and data transfer between different levels of phenomena description. In the framework of the approach, unknown properties of molecules, ions and atoms (structure, potential energy curves, transition dipole moments) are calculated based on quantum-chemical methods. The calculation results are used to evaluate rate characteristics of physical and chemical processes. The developed kinetic state-to-state scheme is then used to calculate the macro properties of the system under investigation. As an example of the multilevel approach, the emission properties of the Ar–GaI3 positive column discharge plasma were calculated using the Chemical Work Bench computational environment. The calculations yield the electron energy balance and emission efficiency as functions of plasma parameters.