. Author manuscript; available in PMC: 2019 Mar 28.

Published in final edited form as: Phys Chem Chem Phys. 2018 Mar 28;20(13):8432–8449. doi: 10.1039/C7CP08185E

Table 4.

Pair-specific NBFIX corrections to the CHARMM36 force field¹⁴. The table lists corrections to the LJ R_min parameters of the specified atom pairs. The corrections are given relative to the standard force field values and have units of Angstroms. Mg²⁺ and Ca²⁺ are modeled as permanent hexahydrate and heptahydrate complexes, respectively, with the water dipole moments increased by 1 or 0.5 Debye, respectively, above the standard TIP3P value^31,51. The NBFIX corrections are for the atom pairs formed by monovalent ions, water oxygens of Mg²⁺ hexahydrates and Ca²⁺ heptahydrates, nitrogen atom of a positively charged amine group (N–H), nitrogen atom of a guanidinium group (N=C), acetate oxygen (O=C), phosphate oxygen (O=P), and sulfate oxygen (O=S). Superscripts §, ¶ and * correspond to Refs. 31, 41, and 51, respectively, which detail validation of the specific corrections. The value of 0.00 indicates that no NBFIX correction is needed to reproduce the osmotic pressure experiment using the standard parameter set. Br⁻ and I⁻ anions are not listed because they are not included in the standard CHARMM36 force field. The CUFIX-corrected parameter set in the CHARMM format is available at http://bionano.physics.illinois.edu/CUFIX.

	Li⁺	Na⁺	K⁺	Rb⁺	Cs⁺	Mg²⁺	Ca²⁺	N–H	N=C
Cl⁻	0.23^§	0.06^§	0.05^§	0.022 ^{Fig. S6A}	0.00 ^{Fig. S6B}	0.015^§	0.011*	0.03^¶	0.03^¶
O=C	0.19^§	0.09^§	0.08^§	0.056 ^{Fig. S7A}	0.00 ^{Fig. S7B}	0.055^§	0.079*	0.08^¶	0.20 ^{Fig. 5B}
O=P	0.19^§	0.09^§	0.08^§	0.056 ^{Fig. S7A}	0.00 ^{Fig. S7B}	0.055^§	0.079*	0.16^¶	0.16^¶
O=S	0.19^§	0.09^§	0.08^§	0.056 ^{Fig. S7A}	0.00 ^{Fig. S7B}	0.055^§	0.079*	0.16^¶	0.16^¶