For orthorhombic, rhombohedral and simple cubic allotropes, the dependences of Gibbs energy on temperature and pressure were found based on the temperature dependence of Gibbs energy of white phosphorus in the form . Molar volumes (V 0 ), 300-K bulk moduli (B 0 ), their first pressure derivatives (B 0 ), and volume thermal expansion coefficients of solid phosphorus allotropes were taken from ; pressure dependencies of molar volumes were represented using the Murnaghan approximation .