Origin of the transition entropy in vanadium dioxide

Mellan, T. A., Wang, H., Schwingenschlögl, U. and Grau-Crespo, R. ORCID: https://orcid.org/0000-0001-8845-1719 (2019) Origin of the transition entropy in vanadium dioxide. Physical Review B, 99 (6). 064113. ISSN 1098-0121 doi: 10.1103/PhysRevB.99.064113

Abstract/Summary

The reversible metal-insulator transition in VO2 at TC = 340 K has been closely scrutinized yet its thermodynamic origin remains ambiguous. We discuss the origin of the transition entropy by calculating the electron and phonon contributions at TC using density functional theory. The vibration frequencies are obtained from harmonic phonon calculations, with the soft modes that are imaginary at zero temperature renormalized to real values at TC using experimental information from diffuse x-ray scattering at high-symmetry wavevectors. Gaussian Process Regression is used to infer the transformed frequencies for wavevectors across the whole Brillouin zone, and in turn compute the finite temperature phonon partition function to predict transition thermodynamics. Using this method, we predict the phase transition in VO2 is driven five to one by phonon entropy over electronic entropy, and predict a total transition entropy that accounts for 95% of the calorimetric value.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/82158
Item Type	Article
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Uncontrolled Keywords	metal-insulator transition, thermodynamics, phonon entropy, VO2, Gaussian Process Regression
Publisher	American Physical Society
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