Developing machine-learned potentials to simultaneously capture the dynamics of excess protons and hydroxide ions in classical and path integral simulations
Developing machine-learned potentials to simultaneously capture the dynamics of excess protons and hydroxide ions in classical and path integral simulations
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DOI：
10.1063/5.0162066
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发表时间：
2023-08-21
影响因子：
4.4
通讯作者：
Markland, Thomas E.
中科院分区：
文献类型：
--
作者：
Atsango, Austin O.;Morawietz, Tobias;Markland, Thomas E.
过量质子和氢氧根离子在水中的传输是许多重要的化学和生物过程的基础。准确地模拟相关的传输机制理想地需要利用从头算分子动力学模拟来模拟质子转移和路径积分模拟中涉及的键断裂和形成，以模拟与轻氢原子相关的核量子效应。这些要求导致令人望而却步的计算成本，特别是在收敛质子输运性质所需的时间和长度尺度上。在这里，我们提出了机器学习的潜力（MLP），可以在广义梯度近似和混合密度泛函理论的精度水平上模拟过量质子和氢氧根离子，并使用它们来执行多纳秒的经典和路径积分质子缺陷模拟，其成本仅为相应从头算模拟的一小部分。我们表明，MLP是能够再现从头算的趋势和收敛性能，如过量质子和氢氧根离子的扩散系数。我们使用我们的多纳秒模拟，这使我们能够监测大量的质子转移事件，分析超配位在氢氧离子的运输机制中的作用，并提供进一步的证据，过量的质子和氢氧离子之间的扩散不对称。
The transport of excess protons and hydroxide ions in water underlies numerous important chemical and biological processes. Accurately simulating the associated transport mechanisms ideally requires utilizing ab initio molecular dynamics simulations to model the bond breaking and formation involved in proton transfer and path-integral simulations to model the nuclear quantum effects relevant to light hydrogen atoms. These requirements result in a prohibitive computational cost, especially at the time and length scales needed to converge proton transport properties. Here, we present machine-learned potentials (MLPs) that can model both excess protons and hydroxide ions at the generalized gradient approximation and hybrid density functional theory levels of accuracy and use them to perform multiple nanoseconds of both classical and path-integral proton defect simulations at a fraction of the cost of the corresponding ab initio simulations. We show that the MLPs are able to reproduce ab initio trends and converge properties such as the diffusion coefficients of both excess protons and hydroxide ions. We use our multi-nanosecond simulations, which allow us to monitor large numbers of proton transfer events, to analyze the role of hypercoordination in the transport mechanism of the hydroxide ion and provide further evidence for the asymmetry in diffusion between excess protons and hydroxide ions.