A fast polarizable water model for atomistic simulations.

Simulating water accurately has been a major challenge in atomistic simulations for decades. Inclusion of electronic polarizability effects holds considerable promise, yet existing approaches suffer from significant computational overhead compared to the widely used non-polarizable water models. We have developed a globally optimal polarizable water model, OPC3-pol, that explicitly accounts for electronic polarizability with minimal impact on computational efficiency. OPC3-pol reproduces five key bulk water properties at room temperature with an average relative error of 0.6%. In atomistic simulations, OPC3-pol’s computational efficiency is in-between that of 3- and 4-point non-polarizable models; the model supports increased (4 fs) integration time step. OPC3-pol is tested in simulations of a globular protein and a B-DNA dodecamer with recent AMBER force-fields, demonstrating structure stability close to reference at multi-microsecond time-scale. The model can be trivially adopted by any package that supports standard non-polarizable force-fields and water models; its intended use is in long classical atomistic simulations where water polarization effects are expected to be important.