Collectively, energy minima and energy maxima are referred to as stationary points Energy minima(or more precisely, local minima) correspond to stable molecules(reactants and products), although some energy minima may be too reactive to allow easy isolation and characterization intermediates). The lowest energy local minimum is termed the global minimum. The positions of the energy minima along the reaction coordinate correspond to their equilibrium geometries, and their relative energies relate to their(relative) thermochemical stabilities. Thus, the overall process depicted above is exothermic, meaning that it is thermodynamically favorable.
Energy maxima on the potential energy surface correspond to transition states, and their positions along the reaction coordinate correspond to transition state geometries. These cannot be determined experimentally. The energies of the maxima relative to those of energy minima correspond to activation energies and may be related to reaction rates. "Real reactions" may involve several distinct steps(and one or more intermediates), and their overall rates are usually assumed to be that of the step which involves the highest-energy transition state(the"rate-limiting step"). Finally, the curvature of the potential energy surface in the vicinity of a minimum(as given by its second derivatives or Hessian) relates directly to a molecule's vibrational spectrum.