Calculation of the thermodynamic properties of AIII nitrides

The enthalpies of formation of three AIII nitrides, AlN, GaN, and InN with wurtzite-type structure, were assessed using an ab initio density functional theory approach. A full-potential LAPW method within the generalized gradient approximation implemented in the WIEN2k package was employed to obtain the total cohesive energies of AIIIN, the corresponding metallic elements and the N2 molecule. Furthermore, the entropies and specific heats at T=298.15K were obtained from an analysis of the low temperature heat capacity data using a Debye–Einstein model. The total energies and the integrated low-temperature heat capacities were eventually combined to evaluate the resulting heats of formation of AIIIN at T=298.15K.