DPPC lipid membrane bilayer

We have carried out molecular dynamics simulations of 256 DPPC lipid molecules forming a membrane bilayer and 6888 water molecules up and down the membrane. The total number of atoms in the system was 30464 and the size of the system was approximately 80x80x75Å. This is how it looks like:

The NPT-molecular dynamics algorithm (i.e. separate pressure controll in each direction) was employed. The GROMOS force field with rigid bonds (constrained by the SHAKE algorithm) was used. The cut-off distance was 16Å. The long-range electrostatic interaction are taken into account by Ewald method. On Helge, we are able to run 20 ps of molecular dynamics of this system per day, using 2 fs MD steps.