A relation between the systematic errors of a quantum chemical potential and of fluid properties calculated from it

For five ab initio potentials applied in simulations it was observed that t he pressure vs. temperature curves at constant density are shifted parallel to the experimental curves. This allows extrapolation of the simulation re sults to the values that would have been obtained with exact potentials. An explanation based on model calculations is given, showing that this effect results from a systematic compensation for the changes induced by variatio n in the potential depth and equilibrium distance. (C) 2001 Published by El sevier Science B.V. All rights reserved.