Understanding emergent phenomena of fluids under physical confinement requires the development of advanced tools for rapid and accurate simulation of their physiochemical properties. Simulating liquid molecules commensurate in size with the nanoscale enclosures that confine them is a key challenge. We demonstrate an accelerated molecular dynamics simulation technique that combines soft-core potentials (SCP) and simulated annealing (SA) to analyze confined liquids. This integrated SCP/SA method relies on a new spliced soft-core potential (SSCP), which enables tunable accuracy with respect to the target hard-core potential (HCP). SCP/SA enables the packing of enclosures with bulk material in a controlled, thermodynamically consistent manner. The enhanced SSCP accuracy is a critical feature of SCP/SA, enabling a smooth transition between the SCP and the HCP at a desired SCP hardness. We applied SCP/SA to the problem of filling a carbon nanotube (CNT) in periodic boundary conditions with a popular ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM⁺][PF₆^–]. We performed a series of triplicate simulations on systems with varying CNT diameter and charge to demonstrate SCP/SA’s versatility. Beyond this IL/CNT system, the SCP/SA simulation framework has a broad range of potential applications, not limited to nanoscale enclosures and interfaces, including both solid-state and biological systems.

中文翻译：

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将液体限制在碳纳米管内部：具有剪接的软核电势和模拟退火的加速分子动力学

要了解在物理限制条件下出现的流体现象，需要开发先进的工具来快速，准确地模拟其物理化学性质。一个关键的挑战是模拟大小与限制它们的纳米级外壳相对应的液体分子。我们展示了一种结合了软核电势（SCP）和模拟退火（SA）来分析受限液体的加速分子动力学模拟技术。这种集成的SCP / SA方法依赖于新的拼接软核电势（SSCP），这使得相对于目标硬核电势（HCP）的可调精度成为可能。SCP / SA能够以受控的，热力学上一致的方式用散装物料包装外壳。SSCP准确性的提高是SCP / SA的一项重要功能，使SCP和HCP在所需的SCP硬度下平稳过渡。我们将SCP / SA应用于在周期边界条件下用流行的离子液体（IL）1-丁基-3-甲基咪唑六氟磷酸盐[BMIM]填充碳纳米管（CNT）的问题⁺ ] [PF ₆ ^– ]。我们在具有不同CNT直径和电荷的系统上进行了三次重复的模拟，以证明SCP / SA的多功能性。除此IL / CNT系统之外，SCP / SA模拟框架还具有广泛的潜在应用，不仅限于纳米级外壳和接口，包括固态和生物系统。