Importance of the Hubbard correction on the thermal conductivity calculation of strongly correlated materials: a case study of ZnO.

Anthony Consiglio,Zhiting Tian

doi:10.1038/srep36875

Abstract

The wide bandgap semiconductor, ZnO, has gained interest recently as a promising option for use in power electronics such as thermoelectric and piezoelectric generators, as well as optoelectronic devices. Though much work has been done to improve its electronic properties, relatively little is known of its thermal transport properties with large variations in measured thermal conductivity. In this study, we examine the effects of a Hubbard corrected energy functional on the lattice thermal conductivity of wurtzite ZnO calculated using density functional theory and an iterative solution to the Boltzmann transport equation. Showing good agreement with existing experimental measurements, and with a detailed analysis of the mode-dependence and phonon properties, the results from this study highlight the importance of the Hubbard correction in calculations of thermal transport properties of materials with strongly correlated electron systems.

Highlights

Fully considers the on-site correlations, such as dynamical mean-field theory, could theoretically produce even better predictions, yet at a much higher computational cost
In this study we analyzed the effect of Hubbard corrected density functional theory (DFT) energy functionals (DFT+U) on the thermal conductivity of ZnO using a PBE pseudopotential, and compared our results to LDA9 calculations and experimental laser flash method[7,10,11] and SThM8,12 measurements
We found that both PBE and LDA underestimated the thermal conductivity of ZnO and their agreements with the laser flash method values on unknown sample conditions are more of a coincidence

Summary

Introduction

Fully considers the on-site correlations, such as dynamical mean-field theory, could theoretically produce even better predictions, yet at a much higher computational cost. This DFT+U method has been applied, by Calzolari et al for dielectric properties of ZnO13, obtaining good agreement with experimental values, at the same computational cost. The correction, is a good compromise between accuracy and computational demands, and should be included because the correct description of the electronic band structure and phonon dispersion are important for reliable predictions of the lattice thermal conductivity of strongly correlated materials

Methods

Results

Conclusion