Potential of mean force for an aqueous chloride ion pair : simulation with a polarizable model

The potential of mean force for an aqueous chloride ion pair at room temperature is calculated using a polarizable-polar model and molecular dynamics computer simulation. A shallow minimum in the potential of mean force is observed near an ion separation of 4.8 Å, with approximately two water molecules bridging the chloride ions at this separation. The barrier to further separation is less that 1 kcal/mol. This result does not support the strong association of chloride ion pairs.