Much molecular modeling uses classical fixed-charge force fields without an explicit accounting for polarization . Such two-body additive force fields are implicitly polarized to hopefully match a level of polarization appropriate on average for condensed-phase simulations . This is true for common force fields in the AMBER, CHARMM, GROMOS and OPLS-AA families (e.g. GAFF , OpenFF , CGenFF , and OPLS-AA ); these neglect polarization for computational efficiency. It's possible that the approximations made by these fixed-charge force fields may result in particularly large errors in systems like those examined here .