Tee Shern R, Searles Debra J
Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia.
J Chem Phys. 2022 May 14;156(18):184101. doi: 10.1063/5.0086986.
Molecular dynamics (MD) simulations of complex electrochemical systems, such as ionic liquid supercapacitors, are increasingly including the constant potential method (CPM) to model conductive electrodes at a specified potential difference, but the inclusion of CPM can be computationally expensive. We demonstrate the computational savings available in CPM MD simulations of ionic liquid supercapacitors when the usual non-periodic slab geometry is replaced with fully periodic boundary conditions. We show how a doubled cell approach, previously used in non-CPM MD simulations of charged interfaces, can be used to enable fully periodic CPM MD simulations. Using either a doubled cell approach or a finite field approach previously reported by others, fully periodic CPM MD simulations produce comparable results to the traditional slab geometry simulations with a nearly double speedup in computational time. Indeed, these savings can offset the additional cost of the CPM algorithm, resulting in periodic CPM MD simulations that are computationally competitive with the non-periodic, fixed charge equivalent simulations for the ionic liquid supercapacitors studied here.
复杂电化学系统的分子动力学（MD）模拟，如离子液体超级电容器，越来越多地采用恒电位法（CPM）来模拟处于特定电位差的导电电极，但采用CPM计算成本较高。我们证明，当用完全周期性边界条件取代通常的非周期性平板几何结构时，离子液体超级电容器的CPM MD模拟可节省计算量。我们展示了一种先前用于带电界面非CPM MD模拟的双胞方法，如何用于实现完全周期性的CPM MD模拟。使用双胞方法或其他人先前报道的有限场方法，完全周期性的CPM MD模拟产生的结果与传统平板几何结构模拟相当，计算时间加快了近一倍。实际上，这些节省可以抵消CPM算法的额外成本，从而使周期性CPM MD模拟在计算上与这里研究的离子液体超级电容器的非周期性、固定电荷等效模拟具有竞争力。
