To reveal the transition from exo-TCD-chair to exo-TCD-boat, that is, the energy variations as the chair-boat dihedral angle, we performed relaxed potential energy scan for the isomers in As displayed in Figure , although the energy difference between chair and boat is very small, to transfer from chair to boat needs to cross the calculated energy barrier as high as 3.65 kcal/mol, which needs the temperature to rise to as high as 1836.6 K without catalysts. It is noted from ignition delay measurements that for JP-10/air and JP-10/additive blends in air, the temperatures can rise in the range of 1200 to 2500K under various pressures from 10 to it is possible that the JP-10 fuel exo-TCD-chair and boat isomers co-exist. As a result, property information of the fuel under the isomer forms provides useful information.