Thermodynamic properties of BP polymorphs have been calculated from the phonon frequencies using the statistical thermodynamic expressions on a high precision sampling mesh in the Brillouin zone. The properties of all three polymorphs were found to be very similar over a wide temperature range. Fig. shows the temperature changes of heat capacity at constant volume C V , entropy S and Helmholtz free energy F = U -TS, where U is the internal energy, S is the entropy and T is the absolute temperature.