Berlin 2012 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 45: Computational Materials Modelling VI - Thermal Conductivity and Transport
MM 45.1: Talk
Thursday, March 29, 2012, 10:15–10:30, TC 006
Thermal Conductivities at High Temperatures from First Principles — •Christian Carbogno1, Rampi Ramprasad2, and Matthias Scheffler1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4–6, 14195 Berlin, Germany — 2Chemical, Materials & Biomolecular Engineering, University of Connecticut, Storrs, USA
In spite of significant research efforts, a first principles determination of the thermal conductivity at high temperatures has remained elusive. Under such conditions, techniques that rely on the harmonic approximation become questionable, while non-equilibrium MD methods require huge temperature gradients that lead to undesired non-linear effects. The Green-Kubo method, which does not suffer from these shortcomings, involves the assessment of the thermal conductivity from the auto-correlation of the heat flux via equilibrium MD. This method has hitherto been disregarded in first-principles simulations since the computation of the heat flux requires the energy contributions from the individual atoms, a quantity that is not directly accessible in first-principles schemes. We show that the Green-Kubo approach can be reformulated in terms of the energy density [1], which is directly accessible in density functional theory calculations. This approach leads to a unique definition of the heat flux that does not rely on any partitioning scheme for the total energy. To demonstrate the capabilities of this technique, we investigate the thermal conductivity of ZrO2, a material that is widely used in industrial high-temperature applications.
[1] N. Chetty and R. M. Martin, Phys. Rev. B 45, 6074 (1992).