Nonlinear thermal response of a Lennard-Jones fluid near the triple point

We have carried out some more nonlinear molecular-dynamics calculations of the conductivity of the Lennard-Jones fluid near its triple point as a function both of the number of particles and of the external field. We have employed the subtraction technique and Evans-Gillan algorithm together with a recently proposed criterion to compare the strengths of impulsive and stationary perturbations. Accordingly, the gradients we used lie in the range 1.2×${10}^7$ to 5.8×${10}^9$ K/cm. Our results suggest that the response of the energy current at K=0 is linear for F̃ up to 5.8×${10}^8$ K/cm. We find nonlinearity for larger values of the perturbation. No dependence of the response on the particle number is found.