title: Amber Lipid17 Simulations of POPC/POPS Membranes with CaCl2
author: Batuhan Kav
description: System: Simulations of POPC/POPS (5:1, 144 lipids in total) membranes with  various CaCl2 concentrations.  Number of POPS: 24. Number of POPC 120. Number of waters: 5760 (excluded from uploaded trajectories) Number of Ca+2 Ions: 52 (500mm), 104 (1000mm), 208 (2000mm), 311 (3000mm), 415 (4000mm) Lipid model: Amber Lipid 17 [IR Gould, AA Skjevik, CJ Dickson, BD Madej, RC Walker: "Lipid17: A Comprehensive AMBER Force Field for the Simulation of Zwitterionic and Anionic Lipids" in prep. (2018)]. Ion models:  Li/Merz Ions [Li, P. J. Chem. Theory Comput. 9 2733-2748 (2013)]. Water model: TIP3P [WL Jorgensen, J Chandrasekhar, JD Madura, RW Impey, ML Klein J. Chem. Phys. 79 926 (1983)]. Simulation engine: Amber16 [DA Case et al. AMBER 2017 UCSF (2017)]. Number of independent repeats per setup: 2. Trajectory lengths per repeat: 200 ns. Previously equilibrated for: 300 ns. Sampling rate: every 10 ps. Time integration step: 2 fs. Thermodynamic ensemble: NpT.  Temperature coupling: 'Langevin' at T = 298 K. Pressure coupling: 'Berendsen' [J. Chem. Phys. 81 3684 (1984); J. Chem. Phys. 103 10252 (1995)] with xy and z coupled separately at p = 1.0 bar with no surface tension. Electrostatics: PME [J. Chem. Phys. 98 10089 (1993); J. Chem. Theory Comput. 9 3878 (2013)]. Van der Waals: Turned off between 1.0 nm and 1.5 nm. Constraints: Lengths of covalent bonds involving Hydrogens in lipids using SHAKE [J. Comput. Phys. 23 327 (1977)], in water using SETTLE [J. Comput. Chem. 13 952 (1992)]. Used in publications: OHS Ollila et al. "NMRlipids IV: Headgroup & glycerol backbone structures, and cation binding in bilayers with PS lipids" in prep (2018).