A reaction class approach for modeling gas phase reaction rates

We present a series of new tunneling models based on a reaction class appro ach. Reaction class consists of all reactions that have the same reactive m oiety. One can expect that reactions in the same class share similarities i n the shape of the potential energy surfaces along the reaction path. By ex ploring such similarities, we propose to use reaction path information from the parent (smallest) reaction in calculations of tunneling contributions of larger reactions in the class. This significantly reduces the computatio nal cost while maintaining the accuracy of the model.