Figure 1.
Comparisons of WLW and WVW systems.
Snapshots of the time evolution of water-lipid-water (WLW) and water-vacuum-water (WVW) configurations under an external electric field of 500 MV/m. (a) WLW configuration at times 5.8, 6.7, and 7.3 ns from the start of the simulation with both water molecules (oxygen–red, hydrogen-gray) and lipid molecules (phosphorus-yellow, nitrogen-blue, lipid tail groups–silver) displayed. (b) same WLW data as in (a) but with only water molecules shown. (c) WVW configuration at times 1.157, 1.160, and 1.194 ns.
Figure 2.
Average pore initiation times for WLW and WVW systems calculated with three sets of simulations for each configuration.
Figure 3.
Protrusion molecules identification.
XZ-projection of the water molecules positions in a typical WVW simulation at the times (a) just before protrusion begins to grow and (b) just before it begins to interact with/attract water molecules from the other side of the gap. Protrusion molecules are colored in red and the rest of the water molecules are shown as blue.
Figure 4.
Anti-correlation of protrusion height and total interaction energy.
Graphs demonstrating anti-correlation between the increase of the protrusion height (black curve) and the decrease of the total interaction energy per protrusion molecule of protrusion waters with all other water molecules (both in the protrusion and in bulk) for (a) WLW (red curve) and (b) WVW (blue curve) simulations.
Figure 5.
Pearson correlation coefficients.
Histograms of the Pearson correlation coefficients demonstrating anti-correlation between the increase of the protrusion height and the decrease of the total interaction energy per protrusion molecule of protrusion waters with all other water molecules (both in the protrusion and in bulk) for (a) WLW and (b) WVW simulations.
Figure 6.
Constituent terms of total interaction energy.
Comparison of constituent terms of the total interaction energy per protrusion molecule between WLW (red curve) and WVW (blue curve) simulations: (a) dipole–external electric field interaction energy, (b) electrostatic interaction energy, (c) Lennard-Jones interaction energy.
Figure 7.
Correlation between protrusion height and total interaction energy in WLW.
A graph (a) and a histogram of the correlation coefficient (b) demonstrating positive correlation between the protrusion height growth and the increase in the total interaction energy between the protrusion waters and the lipids in WLW simulations.
Figure 8.
Energetic comparison of vertical vs. planar dipole configurations.
Total energies of dipole configurations (I) and (II). Dashed line–sum of dipole-dipole interaction and dipole-electric field interaction terms for a horizontal layer of oriented dipoles (configuration (I)), solid line–sum of dipole-dipole interaction, dipole-electric field interaction, and the total solvation energy required to remove the dipoles from the bulk water for the vertical stack of dipoles (configuration (II)).