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O: Fachverband Oberflächenphysik
O 70: Frontiers in Electronic-Structure Theory - Focus on Electron-Phonon Interactions IV (joint session O/CPP/DS/HL)
O 70.6: Vortrag
Mittwoch, 18. März 2020, 16:30–16:45, GER 38
Quantum Nuclear Effects in Thermal Transport of Semiconductors and Insulators — •Hagen-Henrik Kowalski1, Mariana Rossi1,2, Matthias Scheffler1, and Christian Carbogno1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 2MPI for Structure and Dynamics of Matter, Hamburg, Germany
To date, the computation of thermal conductivities relies on either perturbation theory or (ab initio) molecular dynamics (MD) [1]. While perturbative approaches include quantum-nuclear effects (QNE), they typically neglect higher orders of anharmonicity. Conversely, classical MD includes all orders of anharmonicity, but neglects QNEs. To overcome these limitations, we have developed a formalism that accounts for both quantum-nuclear effects and all orders of anharmonicity. For this purpose, the nuclear dynamics are assessed via Thermostatted Ring Polymer MD (TRPMD) [2] and the thermal conductivity is obtained via the Green-Kubo formalism using a newly proposed TRPMD based heat-flux estimator. Using solid Argon and Silicon as model systems, we discuss the influence of QNEs on thermal transport by comparing velocity, energy, and heat-flux autocorrelation spectra. This allows to rationalize the impact of QNEs on vibrational frequencies, lifetimes, and on the thermal conductivity in different temperature regimes.
[1] C. Carbogno, R. Ramprasad, and M. Scheffler, Phys. Rev. Lett. 118, 175901, (2017).
[2] M. Rossi, M. Ceriotti, D. Manolopoulos, J. Chem. Phys. 140, 234116 (2014).