RMG (program)

RMG, short for Reaction Mechanism Generator, is an open-source, automated chemical kinetics software program developed primarily at MIT and Caltech. Its primary function is to predict the chemical reaction mechanisms for gas-phase and liquid-phase chemical processes, particularly combustion and pyrolysis, but also applicable to other areas. RMG aims to generate comprehensive reaction networks based on a relatively small set of user-provided starting materials, thermodynamic data, and transport data, along with a library of predefined reaction families.

The core of RMG lies in its ability to automatically generate reaction mechanisms based on a set of reaction templates. These templates represent common reaction types, such as hydrogen abstraction, addition, and unimolecular decomposition. The software utilizes a graph-based representation of molecules and automatically applies the reaction templates to identify possible reactions and their corresponding rate coefficients.

RMG employs a hierarchical system of estimating reaction rates. Where experimental data is available, it is prioritized. When experimental data is absent, RMG utilizes rate rules based on transition state theory and kinetic data from analogous reactions. In cases where even rate rules are unavailable, RMG can estimate rates based on thermodynamics and structure-activity relationships.

A key feature of RMG is its ability to grow reaction networks iteratively. The software starts with the provided reactants and generates a set of possible products. It then considers these products as potential reactants and continues the process until a desired level of complexity is reached or a convergence criterion is met. This iterative approach allows RMG to explore a vast number of possible reaction pathways and identify the most important reactions.

RMG's output typically consists of a detailed reaction network, including the species involved, the reactions connecting them, and the corresponding rate coefficients. This information can then be used to simulate the chemical process and predict its behavior under various conditions. The program also provides tools for analyzing the reaction network and identifying the rate-determining steps. RMG is used by researchers and engineers in academia and industry for a variety of applications, including the design of new fuels, the optimization of combustion processes, and the development of novel chemical reactors. The program is continuously being developed and improved by a team of researchers.