We computed this observable using the gmx energy routine of GROMACS suite. The experimental reference data of κ T were taken from Ref. Surface tension. The interface between water and void was prepared and simulated following the good practices outlined in Ref. Firstly, a cubic box containing 1024 water molecules was equilibrated in the N P T ensemble. To represent the void phase, the z-axis of the simulation box was elongated by a factor of 4. The resulting biphasic system was then simulated for 50 ns in the N V T ensemble. The surface tension of the water-void interface was calculated using the mechanical or pressure approach, which involves evaluating the inhomogeneity of the pressure tensor as follows: