Ab Initio Studies of Rotation and Solvent Effects for two important membrane molecules: DPPC and DMPC

DPPC (dipalmitoylphosphatidylcholine) and DMPC (dimyristoylphosphatidylcholine) are taken asphospholipids with an equal polar heads and with the difference in the length of hydrocarbonchains. Results obtain from the structural optimization of the isolated DPPC and DMPC in the gasphase, at the Hartree-Fock level of theory by means of STO-3g,3-21G, 6-31G and 6-31G* basissets. the most important dihedral angle of these molecules (DPPC and DMPC) is chosen and theenergy of 14 important atoms were scanned within 180 degrees rotation and sites that have mostchanges are determined and any rotated molecule separately placed in the 19 solvents (The methodis HF/6-31G* model) and then dielectric effect of surrounding were analyzed. The solvent effecton the stability of DPPC & DMPC molecules were discussed using Onsager model.