Polarizable Classical Force Field to Describe the Water/Metal Interfaces in QM/MM Simulations of Electrochemical Interfaces

Electrochemical interfaces are of extreme importance for several technological applications (e.g, fuel cells and biological sensors). However, the microscopic understanding of the kinetic behavior and reactions that occur in water/metal interfaces is still a challenge. Thus, atomistic simulations have proven to be a versatile tool to provide a detailed comprehension of such interfaces at the atomic level. In particular, the mutiscale QM/MM simulations, which take in account both the quantum information and the size of such systems, seem to be an efficient approach to describe the electrode interface. One of the key elements in QM/MM approaches is the classical force field. Particularly for metals, the accuracy of the simulation strongly relies in the ability of the force field to reproduce surface polarization (SP) effects. Based on this, we develop suitable polarizable force fields to describe the water/metal interface. Charged virtual sites (rods) are added to the molecular topology of a simple LJ model in order to create dipoles that reproduce the SP and adsorption properties of the metallic surfaces. We select the water/metal interfaces composed by Pd(111) as model systems to evaluate the performance of the proposed models.