Determining the phonon DOS from specific heat measurements via maximum entropy methods

The maximum entropy and reverse Monte-Carlo methods are applied to the computation of the phonon density of states (DOS) from heat capacity data. The approach is introduced and the formalism is described. Simulated data is used to test the method, and its sensitivity to noise. Heat capacity measurements from diamond are used to demonstrate the use of the method with experimental data. Comparison between maximum entropy and reverse Monte-Carlo results shows the form of the entropy used here is correct, and that results are stable and reliable. Major features of the DOS are picked out, and acoustic and optical phonons can be treated with the same approach. The treatment set out in this paper provides a cost-effective and reliable method for studies of the phonon properties of materials.