Ab initio extension of the AMOEBA polarizable force field to Fe2+
Semrouni, D.; Isley, W., III; Clavaguéra, C.; Dognon, J.-P.; Cramer, C.
J.; Gagliardi, L.
J. Chem. Theor. Comput. 2013, 9, 3062 (doi:10.1021/ct400237r).
We extend the AMOEBA polarizable molecular mechanics force field to the Fe2+ cation in its singlet, triplet, and quintet spin states. Required parameters are obtained either directly from first principles calculations or optimized so as to reproduce corresponding interaction energy components in a hexaaquo environment derived from quantum mechanical energy decomposition analyses. We assess the importance of the damping of point-dipole polarization at short distance as well as the influence of charge transfer for metal-water interactions in hydrated Fe2+; this analysis informs the selection of model systems employed for parameterization. We validate our final Fe2+ model through comparison of molecular dynamics (MD) simulations to available experimental data for aqueous ferrous ion in its quintet electronic ground state.