<div><div>The quantum mechanical/molecular mechanical (QM/MM) method is a hybrid molecular simulation technique that increases the accessibility of local electronic structures of large systems.</div><div> The technique combines the benefit of accuracy found in the QM method and that of cost efficiency found in the MM method.</div><div> However, it is difficult to directly apply the QM/MM method to the dynamics of solution systems, particularly for proton transfer. </div><div> As explained in the Grotthuss mechanism, proton transfer is a structural interconversion between hydronium ions and solvent water molecules. </div><div> Hence, when the QM/MM method is applied, an adaptive treatment, namely on-the-fly revisions on molecular definitions, is required for both the solute and solvent. </div><div> Although several solvent-adaptive methods have been proposed, a full adaptive framework, which is an approach that also considers adaptation for solutes, remains untapped. In this paper, we propose a new numerical expression for the coordinates of the excess proton and its control algorithm.</div><div> Furthermore, we confirm that this method can stably and accurately simulate proton transfer dynamics in bulk water.</div></div>
Proton Transfer in Bulk Water using the Full Adaptive QM/MM Method: Integration of Solute- and Solvent-Adaptive Approaches
