Thermodynamic excess properties and their scaling behavior for the Gaussian core model fluid

The thermodynamic excess properties for the Gaussian core model (GCM) fluid are calculated from an equation of state for the pressure and the internal energy. The equation of state is obtained from extensive Monte Carlo simulation data. Entropy–energy correlations as well as Rosenfeld's scaling laws for the temperature dependence of the excess entropy and internal energy are analysed. The predicted T−2/5 scaling of the excess entropy and T3/5 scaling of the internal energy at constant density is fairly well fulfilled for the GCM. It is shown that an excess entropy-based freezing criterion is approximately valid on the low-density side of the solid state region. Contrary to this, the freezing criterion is violated on the high-density (anomalous) side of the GCM. Finally, pressure–energy correlations are discussed by analysing the corresponding correlation and scaling coefficients. The results confirm the expectation that the GCM is not a strongly correlating liquid, and that therefore Rosenfeld's excess entropy scaling of transport coefficients fails for the GCM.

► Excess entropy directly from the equation of state (EOS) by isothermal integration. ► Thermodynamic integration without bypassing the solid-state region. ► Detailed analysis of Rosenfeld's scaling laws of the Gaussian core model (GCM) fluid. ► Discussion of the properties of strongly correlating liquids by analysing the EOS.