For the two phases, the free energy decreases with temperature as expected from the equation above because S increases with T almost linearly as it can be seen in both panels. In Fig. , the entropy S and the heat capacity are close to zero up to 100 K. Above 100 K, S increases continuously and almost linearly up to the highest temperatures. For the heat capacity curves, a validation of the evolution of C v was found from experimental data on diamond's heat capacity up to high temperatures obtained by Victor back in 1962 . The discrete experimental points obtained from 300K up to 1000K by steps of 100K are plotted as open symbols on the calculated curve (green). An excellent agreement can be observed, except for the last two points at the highest temperature. While supporting our calculated results, this feature is interesting and may raise the remark as to the stability of the measurements and of diamond sample at such high temperatures.