Parameterization of Highly Charged Metal Ions Using the 12-6‑4 LJ-Type Nonbonded Model in Explicit Water

Highly charged metal ions act as
catalytic centers and structural
elements in a broad range of chemical complexes. The nonbonded model
for metal ions is extensively used in molecular simulations due to
its simple form, computational speed, and transferability. We have
proposed and parametrized a 12-6-4 LJ (Lennard-Jones)-type nonbonded
model for divalent metal ions in previous work, which showed a marked
improvement over the 12-6 LJ nonbonded model. In the present study,
by treating the experimental hydration free energies and ion–oxygen
distances of the first solvation shell as targets for our parametrization,
we evaluated 12-6 LJ parameters for 18 M­(III) and 6 M­(IV) metal ions
for three widely used water models (TIP3P, SPC/E, and TIP4PEW). As expected, the interaction energy underestimation of the 12-6
LJ nonbonded model increases dramatically for the highly charged metal
ions. We then parametrized the 12-6-4 LJ-type nonbonded model for
these metal ions with the three water models. The final parameters
reproduced the target values with good accuracy, which is consistent
with our previous experience using this potential. Finally, tests
were performed on a protein system, and the obtained results validate
the transferability of these nonbonded model parameters.