They correspond to saddle points on a PES and are designated by a double dagger.
Algorithms for finding these things are tested on OptBench, which includes the LJ38 and Heptamer Island test cases. The "climbing image" method is a modification of an algorithm used to find these things which adds spring forces along a pathway. Lorquet's nonadiabatic theory of these things allows for nonrelativistic coupling to cause mixed states. They are most commonly found using the synchronous transit or (*) nudged elastic band methods, and they resemble the end state closest in free energy to them according to Hammond's postulate. They correspond to saddle points on a PES and are designated by a double dagger. The Arrhenius equation is used to find the energy of these things, which is called the activation energy. For 10 points, name these locally-maximal energy intermediates in a chemical reaction.
Algorithms for finding these things are tested on OptBench, which includes the LJ38 and Heptamer Island test cases.
transition state [or activated complex]