Force-field based modeling of redox reactions
Wolf Dapp, Forschungszentrum Jülich, Jülich, Germany
Calculating the Coulomb forces in Molecular Dynamics (MD), the effective atomic charge on each atom must be known accurately. While there are several approaches (QE, AACT) for this task, they each have shortcomings. Split Charge Equilibration (SQE) is a method combining the beneficial aspects of both QE and AACT, while avoiding their deficiencies, such as predicting a wrong charge distribution among dissociation of dimers.
To date, partial atomic charges are either assumed constant or assigned according to minimization principles that are smooth and unique functions of the instantaneous atomic coordinates. Thus, charge-transfer history effects cannot be accounted for. Such occur for instance during contact-induced charge transfer between two solid bodies. In particular, redox reactions involve a quasi-discontinuous change of the electronic state, without significant atomic rearrangement.
RedoxSQE, an extension to SQE, assigns discrete oxidation states to each atom. This enables us to model redox reactions. This talk will show proof-of-concept applications, including a complete atomistic nano battery, which self-consistently shows many generic properties of macroscopic batteries. Among other applications, redoxSQE can help to better understand the processes happening at the electrode-electrolyte interface of a real battery.