The molecular structure and phase sequence of simulated LC compound: 4′-pentyloxy-phenyl-2-(5-heptyl)pyrimidine (P-5O7)
MD simulation snapshot of the nematic monolayer at the water interface after 6 ns viewed from the layer normal. The equilibrated structure of P-5O7 laying on the water layer is shown.
MD simulation side-viewing snapshot of the smectic-C monolayer after 6 ns. The equilibrated structure of the smectic monolayer consisting of P-5O7 molecules at the water interface is shown. The molecules tend to be tilted to one particular direction from the layer normal.
Time evolution of the 2D order parameter for the 2D nematic system (blue line) and order parameter of c-director for the 2D smectic-C system (red line). Both systems reach the equilibrated state after 4 ns. Averaged order parameter for the 2D smectic-C is much larger than that for the 2D nematics.
Radial distribution functions for the 2D nematic system and smectic system. Blue curve shows the distribution of the molecular positions for the 2D nematics and red curve is the one for the 2D smectics. These functions are continuous with soft decaying peaks and reaching one constant value. It indicates that both systems behave as liquid not solid.
Mean square displacement as a function of time for the 2D nematic system (a) and smectic system (b) in the equilibrated state. The fact that MSDs grow linearly with time reveals that both systems behave as fluids. The slope of linear approximation line possibly gives us the diffusion constant for the system; 0.82 for the 2D nematic system, and the one for the 2D smectic system is 0.16.
Orientational correlation functions g 2(r) with molecular distance r for the 2D nematic and the 2D smectic systems in the thermally equilibrated state. The obtained values for the 2D nematics are plotted as blue circle points and red square plots are ones for the 2D smectics. The solid lines show that OCFs decay according to the power law of molecular distance: the value of exponent for the nematic monolayer is −1.9 and for the smectic system is −0.20. The inset graph is a log–log plot of g 2(r) indicating that correlation functions decay algebraically.
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