To evaluate the simulation predictions against experiments, we calculated the C-H bond order parameters of α and β segments in the POPC headgroup, which are proportional to the amount of bound charge in a membrane. As shown in Fig. ), a linear decrease in these order parameters is observed as a function of the number of bound etidocaine or TPP molecules to a POPC membrane. This trend is observed in both MD simulations and NMR experiments, but the slope of the decrease depends on force field parameters used in a simulation and deviates from experiments in all cases except for the α carbon in ECC simulations. This indicates that the interactions of these molecules with a POPC lipid membrane are not accurately captured by any of these simulations.