Classical molecular dynamics simulations of various mixtures of POPC:POPS lipid bilayers in water solution with Na+ counterions (or with K+ counterions when noted with "_KCl" suffix) and an additional concentration of NaCl or KCl. The numbers in the file names denote the number of additional cations. ECC-lipids force field parameters used for lipids, SPC/E water model and ECC-ions, all parameters are included in this repository in GROMACS format and are also available at https://github.com/jmelcr/ecc_lipids simulations performed with Gromacs 2018.0 (*.xtc files) simulation length 1000 ns = 1 microsecond temperature 298 K Simulations without additional salts are at a separate deposit: 10.5281/zenodo.1488094.