The melting temperature of the most common models of water

Abstract

The melting temperature of ice Ih for several commonly used models of water (SPC, SPC/E,TIP3P,TIP4P, TIP4P/Ew, and TIP5P) is obtained from computer simulations at p=1bar. Since the melting temperature of ice Ih for the TIP4P model is now known [E. Sanz, C. Vega, J. L. F. Abascal, and L. G. MacDowell, Phys. Rev. Lett. 92, 255701 (2004)], it is possible to use the Gibbs–Duhem methodology [D. Kofke, J. Chem. Phys. 98, 4149 (1993)] to evaluate the melting temperature of ice Ih for other potential models of water. We have found that the melting temperatures of ice Ih for SPC, SPC/E, TIP3P, TIP4P, TIP4P/Ew, and TIP5P models are T=190K, 215K, 146K, 232K, 245K, and 274K, respectively. The relative stability of ice Ih with respect to ice II for these models has also been considered. It turns out that for SPC, SPC/E, TIP3P, and TIP5P the stable phase at the normal melting point is ice II (so that ice Ih is not a thermodynamically stable phase for these models). For TIP4P and TIP4P/Ew, ice Ih is the stable solid phase at the standard melting point. The location of the negative charge along the H–O–H bisector appears as a critical factor in the determination of the relative stability between the Ih and II ice forms. The methodology proposed in this paper can be used to investigate the effect upon a coexistence line due to a change in the potential parameters.