Low-frequency Vibrational Modes of DMPG Lipid Bilayer Studied by Terahertz Spectroscopy and Solid-state Density Functional Theory

We report a study of the low-frequency vibrational modes of the crystalline lipid bilayer of sodium 1,2-dimyristoyl-sn-glycero-3-phosphoryl-3′-rac-glycerol (DMPG) through an interplay between the low-temperature THz spectroscopy and solid-state density functional theory. The normal mode analysis shows the optimized structure is stable (but it may be one of the minima), and a consistent assignment of all the calculated THz bands to the observed ones has been achieved. This result represents the successful calculation of the largest molecule crystalline system, having ever been successfully calculated against the THz spectroscopic evidence to the best of our knowledge.