Phonon dispersion and thermal conductivity of nanocrystal superlattices using three-dimensional atomistic models

MB Zanjani and JR Lukes, JOURNAL OF APPLIED PHYSICS, 115, 143515 (2014).

DOI: 10.1063/1.4870943

A computational study of thermal conductivity and phonon dispersion of gold nanocrystal superlattices is presented. Phonon dispersion curves, reported here for the first time from combined molecular dynamics and lattice dynamics calculations, show multiple phononic band gaps and consist of many more dispersion branches than simple atomic crystals. Fully atomistic three dimensional molecular dynamics calculations of thermal conductivity using the Green Kubo method are also performed for the first time on these materials. Thermal conductivity is observed to increase for increasing nanocrystal core size and decrease for increasing surface ligand density. Our calculations predict values in the range 0.1-1 W/m K that are consistent with reported experimental results. (C) 2014 AIP Publishing LLC.

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