The thermodynamic properties of novel carbon allotropes were calculated from the phonon frequencies using the statistical thermodynamic approach on a high-precision sampling mesh in the Brillouin zone. The temperature dependencies of the heat capacity at constant volume (C v ) and entropy (S) are shown in Fig. in comparison with available experimental C p data for diamond . For all three allotropes, the heat capacity and entropy are higher than those of diamond and increase in the C 5 -C 6 -C 7 series, which is to be expected due to the increasing openness of the crystal structures compared to diamond on the one hand, and the respective conducting versus insulator electronic properties, on the other hand.