(computed with the geometry, frequency, noncovalent, extended tight-binding (GFN1-xTB) method ). The arithmetic mean frequency is A  = 1919 cm -1 , and its harmonic mean frequency is All approximated results are excellent in the region above 1 eV. The agreement deteriorates in the low-energy region near the zero-point energy. The exception is Stirling's approximation with arithmetic mean frequency, which also describes the low energy well. The extended-tocontinuous approximation does not hold the correct behavior at low energies, delivering too hightemperature predictions. the temperatures for the N = 6 EDM with the harmonic mean frequency of H2O2, cm -1 .