A Computational Approach for Modeling Neutron Scattering Data from Lipid Bilayers.

Biological cell membranes are responsible for a range of structural and dynamical phenomena crucial, which are crucial to a cell's well-being and its associated functions. Due to the complexity of cell membranes, lipid bilayer systems are often used as biomimetic models. These systems have led to significant insights into vital membrane phenomena such as domain formation, passive permeation, and protein insertion. Experimental observations of membrane structure and dynamics are, however, limited in resolution, both spatial and temporal. Importantly, computer simulations are starting to play a more prominent role in interpreting experimental results, enabling a molecular understanding of lipid membranes. In particular, the synergy between scattering experiments and simulations offers opportunities for new discoveries in membrane physics, as the length and time scales probed by molecular dynamics (MD) simulations parallel those of experiments. Here, we describe a coarse-grained MD simulation approach that mimics neutron scattering data from large unilamellar lipid vesicles over a range of bilayer rigidities. Specifically, we simulate vesicle form factors and membrane thickness fluctuations determined from small angle neutron scattering (SANS) and neutron spin echo (NSE) experiments, respectively. Our simulations accurately reproduce trends from experiments and lay the groundwork for studies of more complex membrane systems.