The surface tension γ was evaluated separately using a simulation setup consisting of a water film in the NVT ensemble with two liquid-vapor interfaces. We used a tetragonal simulation cell with dimensions 3 nm × 3 nm × 10 nm containing a 3 nm thick water layer normal to the z-dimension with 1024 water molecules in total. A real-space cutoff distance of 15 Å was chosen for nonbonded interactions because the surface tension calculations required accounting for Lennard-Jones interactions at large distances. The other simulation parameters matched the NPT simulations. To evaluate the surface tension for a trajectory frame, we adopted the test-area method with the formula