We have performed a 50 ns of molecular dynamics study of poly(diallyldimethylammonium chloride) (PDADMAC)/sodium dodecyl sulfate (SDS)/decanol/water systems. The influence of the cationic polyelectrolyte on the anionic SDS-based lamellar liquid crystalline system was investigated. The main structural parameters have been calculated and compared with experimental data. We obtain two types of PDADMAC conformation, a more folded structure A and a structure B where the PDADMAC molecule is adsorbed at the anionic head groups of the surfactant molecules. The polyelectrolyte-induced coexistence of two lamellar phases at a concentration of 2-3% of PDADMAC is observed, which is in agreement with experimental findings.

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We have performed the atomistic MD simulation of dimyristoylphosphatidylcholine(DMPC)/dipalmitoylphosphatidylcholine(DPPC) mixed bilayers, consisting of various fraction of lipids, i.e., with fraction 0.25, 0.5 and 0.75 and hydration level 33 water molecules per lipid. The simulations were performed using NAMD code.The area per lipid, densities, orientational order parameters and tilt angle of hydrocarbon chain and also the interdigitation of chains were calculated. It has been established that the interdigitation degree of hydrocarbon chains is increased as the DPPC fraction is decreased. It has been also stated that the area per lipid value in case of racemic mixtures is about 0.72 nm2, which is in good agreement with experimental estimations. The hydrocarbon thickness is increased as the DPPC fraction increased. The DMPC/DPPC mixtures behave as almost ideally mixtures.The diffusion coefficients were also calculated and the results are in agreement with experimental findings.All the calculated parameters were compared with values obtained either from experimental data of DPPC or DMPC depending on the fraction of compound. The reason is that there are no experimental findings on DMPC/DPPC mixtures.