Melting temperature of water: DFT-based molecular dynamics simulations with D3 dispersion correction

Extensive ab initio simulations of ice-water basal interface at seven temperatures in the range 250–400 K were performed in NVT and NPT ensembles with a collection of 389 water molecules in order to estimate the melting point of ice from direct liquid-solid two-phase coexistence. Density functional theory with the BLYP (Becke-Lee-Yang-Parr) exchange-correlation functional and the D3 dispersion correction were used in the expression of total energy. Analysis of density profiles and the evolution of the total potential, or Kohn-Sham plus D3, energy in the simulations at different temperatures resulted in an estimate for melting temperature of ice of 325 K.

Figure 1

Snapshot of equilibrated two-phase system used in ab initio simulations at $T=325$ K. Oxygen and hydrogens are drawn as red and gray spheres, respectively, and the dashed black lines indicate hydrogen bonds.

Figure 2

Oxygen density profiles in the last 5 ps at the seven different simulated temperatures.

Figure 3

Evolution of the potential energy and its cumulative average (dashed lines) at seven temperatures in NVT ensemble.

Figure 4

Average potential energy at different temperatures: NVT simulations—full circles, NPT—open circles.

Figure 5

Profile of the Hartree potential at the different temperatures in a single snapshot configuration.