Anisotropic Thermal Transport in Organic Molecular Crystals from Nonequilibrium Molecular Dynamics Simulations

D Wang and L Tang and MQ Long and ZG Shuai, JOURNAL OF PHYSICAL CHEMISTRY C, 115, 5940-5946 (2011).

DOI: 10.1021/jp108739c

Nonequilibrium molecular dynamics simulations have been performed to study the anisotropic thermal transport in pentacene crystal. At 300 K, a thermal conductivity of 0.72, 1.1, and 0.61 W/mK is obtained in the direction of reciprocal lattice vectors a*, b*, and c*, respectively, in a perfect crystal with the general Amber force field. The performance of the OPLS-UA force field is also examined, which tends to underestimate the thermal conductivity. Effects of isotopic substitutions and vacancies on the thermal conduction are investigated, and it is found that the conductivity decreases rapidly with the vacancy concentration. Our investigations suggest that classical simulations with well chosen force fields may provide reasonable predictions for the thermal transport properties of organic solids. Such predictions are critical in the determination of thermoelectric figure of merit of materials.

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