A quantum theory of these entities would require a non-zero short time limit of the flux-side time correlation function, but theories exist that treat motion on the dividing surface quantum mechanically while treating the other mode classically. These entities may be found by the climbing image variant of the nudged elastic band method, (15[1])and if a corner of a More O’Ferrall—Jencks plot is raised in energy, then this point, which is a first-order (*) saddle point on the potential energy surface, moves towards that corner. Considering these entities in quasi-equilibrium leads to the Eyring equation, and these (10[1])entities most closely resemble the stable species to which they are closest in energy, according to Hammond’s postulate. For 10 points, name these short lived chemical species which, unlike (10[1])intermediates, appear as energy maxima on a reaction coordinate. ■END■