Figure 4.

Representative conformations from MD simulations of lipid-A membranes in the presence of Al³⁺ counterions using the stepwise-thermalization NVT/NPT protocol and two long-range electrostatic approximations. Lipid-A bilayers without (a,b) addition of salts, (c,d) with addition of 150 mM of AlCl₃, and (e,f) with addition of 150 mM NaCl. Long-range electrostatic interactions were approximated using reaction-field (first column) or particle-mesh Ewald (second column). Simulations were run in duplicate for 400 ns after the equilibration phase with the stepwise thermalization protocol. Al³⁺, Na⁺, and Cl⁻ are shown in yellow, magenta, and green van der Waals spheres, respectively.