CALCULATION OF TRANSPORT-PROPERTIES FROM MOLECULAR-DYNAMICS SIMULATION

Using the self-diffusion as an example, we present a novel molecular dynamics method which fixes a transport property of the system to a prescribed value. We discuss the technical realization of the algorithm for this history dependent property. Owing to the monotonic temperature vs self-diffusion relationship for a given model substance at fixed density the system automatically chooses that temperature which corresponds to the input value of the self-diffusion coefficient. In principle, this approach can be applied to other transport coefficients too. In practice, however, the numerical calculation of transport properties expressed by the collective dynamics of particles is very time consuming from equilibrium molecular dynamics simulation. Our method being an equivalent of the Green-Kubo integral also performs poorly compared to nonequilibrium molecular dynamics techniques. We present details and results of model calculations for these two transport processes.