Photo‐switchable lipids are synthetic lipid molecules used in photo‐pharmacology to alter membrane lateral pressure and thus control opening and closing of mechanosensitive ion channels. The molecular picture of how photo‐switchable lipids interact with membranes or ion channels is poorly understood. To facilitate all‐atom simulations that could provide a molecular picture of membranes with photo‐switchable lipids, we derived force field parameters for atomistic computations of the azobenzene‐based fatty acid FAAzo‐4. We implemented a Phyton‐based algorithm to make the optimization of atomic partial charges more efficient. Overall, the parameters we derived give good description of the equilibrium structure, torsional properties, and non‐bonded interactions for the photo‐switchable lipid in its trans and cis intermediate states, and crystal lattice parameters for trans‐FAAzo‐4. These parameters can be extended to all‐atom descriptions of various photo‐switchable lipids that have an azobenzene moiety.
