Equilibrium Chemical Reactions with Khimera
Quantitative data on the rate constants of equilibrium chemical reactions are of great importance for kinetic modeling in combustion, materials, environmental chemistry, plasma chemistry and plasma processing.
Universal Set of Processes Accessible for Treating by Khimera
State of art models of thermal chemical reactions incorporated into Khimera are based on qualitative physical ideas about the character of electronic potential surfaces of the interacting systems. The dynamics is treated within well approved variants of statistical approach.
Example: chain branching reaction O+H2 → OH+H
The reaction O+H2 → OH+H is one of the chainbranching reactions in the practically important process of hydrogen combustion. The rate constant of this reaction was evaluated using the transition state theory. This theory is applicable if only one potential barrier exists on the reaction path from reagents to products and there are no deep potential wells.
The window of the Khimera module with the results of calculations of the rate constant using the Khimera module is shown in the figure along with the available experimental data. It is seen that the transition state theory with the parameters obtained from quantum chemical calculations provides a quantitative description of the direct bimolecular reaction.
Example: chain initiation reaction O2 +C2H6 → HO2 + C2H5
The reaction O2+C2H6→HO2+C2H5 is one of the chain initiation reactions in the practically important process of hydrocarbon low temperature combustion. The rate constant of this reaction was evaluated using the transition state theory. The parameters of the potential surface were evaluated ab initio within the framework of DFT using the Gaussian 98 program package.
The window of the Khimera module with the results of calculations of the rate constant using the Khimera module is shown in the figure along with the available experimental data. It is seen that the transition state theory with the parameters obtained from quantum chemical calculations provides a quantitative description of a bimolecular reaction involving a polyatomic molecule.
Example: soot growth reaction C2H2 + C2H2→C4H3 + H
The reaction C2H2+C2H2→C4H3+H is of importance in the process of soot formation at high temperatures.
The rate constant of this reaction was evaluated using the statistical theory of bimolecular reactions through an intermediate complex. The parameters of the potential surface of the system were evaluated ab initio using the Complete Active Space Self-Consistent Field method and the second order Multi-Reference Moeller-Plesset Perturbation Theory using PC GAMESS/Firefly program package.
The window of the Khimera module with the results of calculations of the rate constant is shown in the picture along with the experimental data. In the present case of strongly discordant experimental results, it can be supposed that theoretical results are more reliable.
