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Theoretical Evaluation of the Thermal Conductivity in Framework (Clathrate) Semiconductors
Published online by Cambridge University Press: 01 February 2011
Abstract
We have calculated the room temperature thermal conductivity in semiconductor germanium clathrates using statistical linear-response theory and an equilibrium molecular dynamics (MD) approach. A key step in our study is to compute a realistic heat-current J (t) and a corresponding auto-correlation function < J (t) J (0) >. To ensure convergence of our results and to minimize statistical fluctuations in our calculations, we have constructed large super-cell models (2944 atoms) and have performed several independent long time simulations (>1,500 ps in each simulation). Our results show an unexpected “oscillator” character in the heat-current correlation function of the guest-free Ge clathrate frameworks. This is absent in the denser diamond phase and other with simple structural frameworks. We seek to interpret these results using lattice dynamics information. A study of the effects of the so-called “rattling” guest atoms in the open-framework clathrate materials is in progress.
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- Copyright © Materials Research Society 2000
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