Figure 1.

The effect of temperature, barostat coupling constant, and long-range electrostatic treatment on the (a) initial pressure and (b) V_L for lipopolysaccharide (LPS)/DPPE bilayers equilibrated under NVT/NPT conditions. The two long-range electrostatics approximations are shown in black (PME) and red (RF). The barostat coupling constants are represented by filled (0.1 ps) or dotted (1.0 ps) symbols and bars. Simulations performed at 200 K and 300 K are shown in circles and triangles, respectively. The inset shows pressure averages at the first step of the NPT phase for direct comparison. (c) Representative configuration of the LPS/DPPE bilayer with the largest value of volume per lipid (dotted black triangles). Only water molecules inside the hydrophobic region of the membrane are shown and near clipping of LPS molecules was applied to improve visualization. Ca²⁺ is shown in green and oxygen and hydrogen in water molecules are in red and white, respectively. Symbols correspond to lps1 (dotted black circles), lps2 (filled black circles), lps3 (dotted red circles), lps4 (filled red circles), lps5 (dotted black triangles), lps6 (filled black triangles), lps7 (dotted red triangles), and lps8 (filled red triangles).