POPC @ 310K, varying amounts of NaCl. Slipids with ECC-scaled ions

Simulations of a POPC bilayer with varying amounts of NaCl.
These simulations were performed as a part of the NMRlipids
project (http://nmrlipids.blogspot.fi). The goal was to study 
the effect of salt on the order parameters of the lipid head 
group and the glycerol backbone. The obtained results are 
reported in the blog.

A POPC bilayer consisting of 200 lipids (100 per leaflet) is 
simulated in the presence of NaCl. Concentrations of 130, 300, 
500, 750, and 1000 mM are employed. The Slipids model [1–3] is 
employed for lipids, tip3p model for water, and the recent ion 
parameters by Kohagen et al. [4] for NaCl. 

The Slipids force field parameters were downloaded from
http://mmkluster.fos.su.se/slipids/

The ion parameters are available at
https://bitbucket.org/hseara/ions/

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The files are named based on the concentration of NaCl
and are in GROMACS format. Trajectories (.xtc) are 
100 ns long with data saved every 100 ps. Additionally,
initial structures (.gro), topology (.top), index (.ndx)
and binary run input files for GROMACS v. 4.6–> (.tpr)
are provided. The run parameter file (.mdp) is general
for all systems.

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[1] Derivation and Systematic Validation of a Refined 
All-Atom Force Field for Phosphatidylcholine Lipids
Joakim P. M. Jämbeck and Alexander P. Lyubartsev
The Journal of Physical Chemistry B 2012 116 (10), 3164-3179
DOI: 10.1021/jp212503e

[2] An Extension and Further Validation of an All-Atomistic 
Force Field for Biological Membranes
Joakim P. M. Jämbeck and Alexander P. Lyubartsev
Journal of Chemical Theory and Computation 2012 8 (8), 2938-2948
DOI: 10.1021/ct300342n

[3] Another Piece of the Membrane Puzzle: Extending Slipids Further
Joakim P. M. Jämbeck and Alexander P. Lyubartsev
Journal of Chemical Theory and Computation 2013 9 (1), 774-784
DOI: 10.1021/ct300777p

[4] Accounting for Electronic Polarization Effects in Aqueous Sodium 
Chloride via Molecular Dynamics Aided by Neutron Scattering
Miriam Kohagen, Philip E. Mason, and Pavel Jungwirth
The Journal of Physical Chemistry B Article ASAP
DOI: 10.1021/acs.jpcb.5b0522