Abstract
We herein present a first-principles formulation of the Green-Kubo method that allows the accurate assessment of the phonon thermal conductivity of solid semiconductors and insulators in equilibrium abinitio molecular dynamics calculations. Using the virial for the nuclei, we propose a unique abinitio definition of the heat flux. Accurate size and time convergence are achieved within moderate computational effort by a robust, asymptotically exact extrapolation scheme. We demonstrate the capabilities of the technique by investigating the thermal conductivity of extreme high and low heat conducting materials, namely, Si (diamond structure) and tetragonal ZrO_{2}.
Highlights
Macroscopic heat transport is a ubiquitous phenomenon in condensed matter that plays a crucial role in a multitude of applications, e.g., energy conversion, catalysis, and turbine technology
We present a first-principles formulation of the Green-Kubo method that allows the accurate assessment of the phonon thermal conductivity of solid semiconductors and insulators in equilibrium ab initio molecular dynamics calculations
The temperature- and pressure-dependent thermal conductivity κðT; pÞ of the material describes the proportionality between heat flux and temperature gradient (Fourier’s law): JðRÞ 1⁄4 −κðT; pÞ · ∇TðRÞ: ð1Þ
Summary
Week ending 28 APRIL 2017 our formalism and demonstrate its wide applicability by investigating the thermal conductivity of Si (diamond structure), which has a especially high thermal conductivity, and tetragonal ZrO2 (P42=nmc), which has a very low thermal conductivity. Using a combined nuclear and electronic energy density, Marcolongo, Umari, and Baroni recently proposed a nonunique formulation of the heat flux and used it to study the convective heat flux in liquids from first principles [21] Their approach is numerically unsuitable for the conductive thermal transport in solids, which features much longer lifetimes and mean free paths. We overcome this limitation by disentangling the different contributions to the heat flux and finding a unique definition for the conductive heat flux in solids This allows us to establish a link to the quasiparticle (phonon) picture of heat transport and to overcome finite time and size effects, as described in the second part of this Letter. We perform the time derivative in Eq (4) analytically [17,18]: JðtÞ 1⁄4 V|1fflfflX fflfflfflIffl{zR_fflfflIfflfflEfflffl}I þ V|1fflfflfflX fflfflIffl{zRfflfflIfflfflEffl_ffl}I: ð5Þ
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
