基于经典与量子模拟的水热容量异常的结构起源
Structural Origin of Water Heat Capacity Anomaly from Classical and Quantum Simulations
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中文总结 AI 辅助
研究水热容量异常的结构起源，采用经典和路径积分分子动力学方法，发现核量子效应抑制高频振动，热容量异常源于结构波动，通过两态映射揭示有效焓标度，建立微观联系。
中文摘要 AI 辅助
在环境条件下，水的等压热容量异常大，过冷时呈现出尖锐的最大值。我们使用具有精确机器学习原子间势的经典和路径积分分子动力学方法表明，核量子效应主要通过抑制高频振动起作用，而等压热容量的异常温度依赖性源于结构波动，由第二溶剂壳侵入序参数量化。一个简单的两态映射揭示了与低密度和高密度样局部结构相互转换相关的约4kJ/mol的有效焓标度，提供了它们的数量变化与过冷到环境条件下的过剩热容量之间的微观联系。
英文摘要
Water isobaric heat capacity is anomalously large under ambient conditions and exhibits a sharp maximum upon supercooling. Using classical and path-integral molecular dynamics with accurate machine-learning interatomic potentials, we show that nuclear quantum effects primarily act by suppressing high-frequency vibrations, while the anomalous temperature dependence of the isobaric heat capacity originates from structural fluctuations, quantified by the second-solvent-shell intruder order parameter. A simple two-state mapping reveals an effective enthalpy scale of about 4 kJ/mol associated with the interconversion of low- and high-density-like local structures, providing a microscopic link between their population changes and the excess heat capacity from supercooled to ambient conditions.
