Correction to “Ab Initio Molecular Dynamics Approach to Quantitative Description of Ion Pairing in Water”

Abstract

Details of classical molecular dynamics simulations Classical molecular dynamics simulations were performed for system consisting of one lithium fluoride (LiF) and 64 water molecules. We tested several force fields for ions (OPLS, Dang, Joung-Cheatham) 1, 2, 3 and two water models (SPC/E and TIP4P). 4, 5 The ion-ion distance interval ranging from 1.75 to 6.0 Å was divided by 0.05 Å. For each of the constrained distance, we collected 10 ns trajectory with a 1fs time step employing the leap frog propagator with the Gromacs software. Simulations were conducted at constant volume with 3D periodic boundary conditions and at temperature of 300 K maintained by a CSVR thermostat 6 with a time constant of 0.2 ps. Note that, at first we simulated in NpT ensemble with Berendsen barostat 7 with time constant of 0.5 ps to obtain an estimate of box size. Then we simulated in NVT ensemble with a box size of 12.6 Å. Short range electrostatic and van der Waals interactions were truncated at 0.6 nm, and the long-range electrostatic interactions were treated by the particle mesh Ewald. 8 Checking the accuracy of the computational setup We checked the influence of the length of the box, of system size by doubling the number of water molecules, and different treatment of short range interactions (cut-off vs. switch) on the mean force. Figure S1 shows mean force as a function of lithium fluoride distance calculated for OPLS ions and 64 or 128 water molecules modeled by TIP4P using different setups.