I’ve seen there are ways to compute the dispersion relation of a crystal from molecular dynamics. An example of how to do this is discussed in this question: Computing phonon dispersion from molecular dynamics simulations?.
Once we have the dispersion relation, my understanding is that we can obtain the phonon Density of States and from it we can compute the partition function and therefore thermodynamic quantities like free energy. However, I have not seen this method used in practice for computing thermodynamic quantities in Molecular Dynamics. Therefore my questions: Is this method actually used in practice? Or is it incorrect to obtain the partition function from dispersion relations computed from molecular dynamics?