First-Principles Computation of the Vibrational Entropy of Ordered and DisorderedNi3Al

There is increasing evidence that vibrational entropy may significantly contribute to the entropy difference between the ordered and the disordered states of a compound. Through first-principles calculations, we investigate the magnitude of this vibrational entropy difference in ${\mathrm{Ni}}_3\mathrm{Al}$, a compound where this effect is believed to be especially large. We find the vibrational entropy difference to be essentially zero and temperature independent.