shown in Figure -top for a few molecules (GFN1-xTB level). They are all systems of astrochemical interest. The difference between Boltzmann and Gibbs volume temperatures is negligible for any system above 24 vibrational degrees (10 atoms). For isolated C60 at 808 K, Deng and Echt 36 measured its heat capacity as 12.6  1.4 meV/K. According to Eq. ( ), this temperature corresponds to E = 14.7 eV, yielding a theoretical estimate of ( ) s G C = 12.0 meV/K (Eq. ( )), in excellent agreement with the experiment. Note that this result is smaller than the high-energy limit, B Nk = 15.0 meV/K (N = 174), due to the nonlinear dependence of the temperature on the energy.