Nonequilibrium molecular dynamics methods for computing the thermal conductivity: application to amorphous polymers

We develop two nonequilibrium simulation methods which are suitable for calculation of thermal conductivity with good accuracy. These methods are based on simple algorithms, and it will be very easy to extend their range of application. In particular, there are no restrictions (from, e.g., the force field) to apply them to a variety of systems. Here, they are applied to the calculation of the thermal conductivity of amorphous polyamide-6,6 systems. We treat two models of the polymer with different degrees of freedoms constrained. The results suggest that the methods are quite efficient, and that thermal conductivity strongly depends on the number of degrees of freedom in the model.