A nonequilibrium molecular dynamics method for thermal conductivities based on thermal noise

Abstract

We developed a nonequilibrium molecular dynamics (NEMD) method for calculating thermal conductivities. In contrast to other NEMD algorithms, here only the heat sink is localized, whereas the heat source can be uniformly distributed throughout the system. The noise due to cutting off the pair forces or to integration errors is such a uniform heat source. In traditional NEMD methods it is normally considered a nuisance factor. The new algorithm accounts for it and uses it. The algorithm is easy to derive, analyse and implement. Moreover, it circumvents the need to calculate energy fluxes. It is tested on the enhanced simple-point charge model for liquid water and reproduces the known thermal conductivity of this model liquid of 0.81 W m(-1) K(-1). It can be generalized to situations, where the thermal noise is replaced by another uniform heat source, or to the inverse situation, where the heat source is localized but the heat sink extends over the entire system.