Modeling non-harmonic behavior of materials from experimental inelastic neutron scattering and thermal expansion measurements. (20th July 2016)

• Record Type: Journal Article
• Authors: Bansal, Dipanshu; Aref, Amjad; Dargush, Gary; Delaire, Olivier
• Is Part Of: Journal of physics. Volume 28:Number 38(2016)
• Publication Date: 2016-07-20
• Subjects: anharmonicity -- aluminum -- FeSi -- free energy -- entropy -- inelastic neutron scattering -- thermal expansion; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/0953-8984/28/38/385201
• Languages: English
• ISSNs: 0953-8984

Abstract

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 F e S i 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.