The comparison suggests that the force field corrections improve the pK a estimates, but more importantly, the lower deviation between the individual replicas (from 0.12 to 0.07 for ASP42, from 0.16 to 0.05 for ASP59, from 0.1 to 0.03 for GLU17, from 0.19 to 0.18 for HIS4, Figure ) suggests that the sampling is improved when the modified force field is used.