The Quantitative MD Study Of Alignment Behavior Of Liquid Crystalat Aploymer Surface

In physics, it is divided into three states of matter, namely solid, liquid andgaseity.Liquid crystal is different from the liquid and crystal , it is an independentmaterial form. It not only has the liquidity of liquid, but also has the anisotropy ofcrystal. The orientation of liquid crystal molecules is one of the key technology ofliquid crystal display,and for the liquid crystal display,alignment can directly impacton the LCD's homogeneity,color, contrast, threshold voltage, response time, viewingangle and other characteristics.According to the theory of polymer alignment that rubbing a polymer surfacecreates grooves with a period of fractions of a micrometer, but on a microscopicscale,it is also believed to order the polymer chains that lie in the surface by drawingthem along the rubbing direction. alignment is primarily due to molecular interactionbetween LC molecules and polymer chains ,an effect that also usually makes themolecules line up in the rubbing direction. The groove theory was that rubbinginduced grooves in the surface, and that with planar anchoring the topography favoredalignment in the direction of rubbing, since in that case no bending elastic energywould be introduced. This paper have used GROMACS to measure aligned 5cbmolecules on a groove surface.We make the model that have a groove surface and contains 506 5cb molecules.Size of the upper half model9.06nm×5.005nm×3.17nm. Size of the lower half4.107nm×5.005nm×3.13nm,and we put the model in the periodic box9.191nm×5.076nm×12.00nm..The analysis of the data mainly has the followingfour aspects:(1) Root Mean Square Deviation(RMSD)of 5cb of N.(2) the distribution of the azimuthal angle.(3) the distribution of the inclination angle.By way of MD simulation we found that there is not only have groove to impact onthe orientation of 5cb ,but also the liquid crystal molecules and the substratemolecular interaction can impact the orientation of 5cb too.The orientation of liquidcrystal molecules is the result of two competing effects ,and this finding hastremendous pushing effect on the development and research of liquid crystal display.