**Comparison of molecular dynamics methods and interatomic potentials for
calculating the thermal conductivity of silicon**

PC Howell, JOURNAL OF CHEMICAL PHYSICS, 137, 224111 (2012).

DOI: 10.1063/1.4767516

We compare the molecular dynamics Green-Kubo and direct methods for
calculating thermal conductivity kappa, using as a test case crystalline
silicon at temperatures T in the range 500-1000 K (classical regime). We
pay careful attention to the convergence with respect to simulation size
and duration and to the procedures used to fit the simulation data. We
show that in the Green-Kubo method the heat current autocorrelation
function is characterized by three decay processes, of which the slowest
lasts several tens of picoseconds so that convergence requires several
tens of nanoseconds of data. Using the Stillinger-Weber potential we
find excellent agreement between the two methods. We also use the direct
method to calculate kappa(T) for the Tersoff potential and find that the
magnitude and the temperature-dependence are different for the two
potentials and that neither potential agrees with experimental data. We
argue that this implies that using the Stillinger-Weber or Tersoff
potentials to predict trends in kappa as some system parameter is varied
may yield results which are specific to the potential but not intrinsic
to Si. (C) 2012 American Institute of Physics.
**http://dx.doi.org/10.1063/1.4767516**

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