(629h) Coulomb without Ewald: Accelerating Charged Molecular Dynamics with Field-Theoretic Simulations

In typical molecular simulations, the evaluation of long-ranged Coulombic interactions are solved using Ewald-based techniques. Yet despite the widespread use of Ewald-based methods, they remain computationally expensive and typically dominate the time required to evaluate the energies and forces in a simulation. In this work, we present an alternative approach for accelerating charged molecular dynamics using field-theoretic simulations. In contrast to particle-based simulations, the Coulomb operator in field-theoretic simulations can be evaluated locally, thereby permitting extremely efficient solutions of charged interactions without the need for costly Ewald-based techniques. Our approach leverages this advantageous feature to substantially accelerate molecular dynamics simulations involving charges. To demonstrate our approach, we show that charged particle and field-theoretic simulations can be constructed to be formally equivalent and yield identical results for both the pressure and chemical potential. Next, we compare the performance of these two methods and show that charged field-theoretic simulations can be three orders of magnitude faster than molecular dynamics simulations despite yielding equivalent results. We lastly illustrate our method for two brief examples: (1) the macrophase separation of oppositely charged polyelectrolytes and (2) the microphase separation of complex coacervate core micelles. Taken together, our work demonstrates that field-theoretic simulations can considerably accelerate calculations involving Coulombic interactions and can enable the study of new systems that are intractable with existing methods.