Bansal, D; Aref, A; Dargush, G; Delaire, O, *Modeling non-harmonic behavior of materials from experimental inelastic neutron scattering and thermal expansion measurements.*,
Journal of Physics. Condensed Matter : an Institute of Physics Journal, vol. 28 no. 38
(September, 2016),
pp. 385201 [doi] .
**Abstract:**

*Based on thermodynamic principles, we derive expressions quantifying the non-harmonic vibrational behavior of materials, which are rigorous yet easily evaluated from experimentally available data for the thermal expansion coefficient and the phonon density of states. These experimentally-derived quantities are valuable to benchmark first-principles theoretical predictions of harmonic and non-harmonic thermal behaviors using perturbation theory, ab initio molecular-dynamics, or Monte-Carlo simulations. We illustrate this analysis by computing the harmonic, dilational, and anharmonic contributions to the entropy, internal energy, and free energy of elemental aluminum and the ordered compound [Formula: see text] over a wide range of temperature. Results agree well with previous data in the literature and provide an efficient approach to estimate anharmonic effects in materials.*