Ab initio Calculation of Transport Properties of Supercritical Carbon Dioxide

Self diffusion, shear viscosity and thermal conductivity of carbon dioxide are determined fully ab initio using two different intermolecular potential energy surfaces. These properties are calculated using the time-correlation formalism in classical equilibrium molecular dynamics simulations. The self diffusion constant is in addition determined from the Einstein relation. For the shear viscosity we use two different models of momentum localization: at the center of mass of the molecules, or at each atom. For the thermal conductivity we apply the formulae for rigid and flexible molecules assuming energy localization at the center of mass of the molecules. The results obtained are in good agreement with experiment. A fully ab initio calculation of transport properties allows for a prediction of these quantities even at state points where experiments are hardly possible.