title: Modeling non-harmonic behavior of materials from experimental inelastic neutron scattering and thermal expansion measurements.
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.
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Dipanshu
authors.initials: D
authors.lastname: Bansal
authors.forename: Amjad
authors.initials: A
authors.lastname: Aref
authors.forename: Gary
authors.initials: G
authors.lastname: Dargush
authors.forename: Olivier
authors.initials: O
authors.lastname: Delaire