For sulfur, results for the II and IV oxidation states will be considered separately due to the large effect of oxidation state on C 6 dispersion coefficients. The average XDM dispersion coefficient for S(II) atoms is 91.8 a.u. and the standard deviation is 2.6 a.u. The coefficient averages for CGenFF and OPLS models are overestimated by more than a factor of two and the range of values are extremely large, with standard deviations of 54.5 and 55.5 a.u., respectively. For the CGenFF force field, this is because of the difference between the disulfide and sulfide atom types; the SG301 atom type (C-S-S-C) has a dispersion coefficient of 209 a.u, while the SG311 atom type (SH, -S-) has a dispersion coefficient of 268 a.u. Sulfolane is the only compound in the test set where the sulfur atom is in the IV oxidation state. The XDM C 6 coefficient for this atom (58 a.u.) is significantly lower than for the S(II) atoms. The CGenFF and OPLS force fields assign the S(IV) atom type (SG302) a dispersion coefficient of 208 a.u., which is lower than for S(II), although it is still overestimated relative to XDM. The GAFF force field assigns S(IV) the same Lennard-Jones parameters as S(II).