Molecular dynamics (MD) is a powerful (and the most viable) tool to compute the thermal conductivities of solid disordered materials. However, conventional classical MD fails to describe the nuclear quantum effects (NQEs), so it may give inaccurate results for light materials at low temperatures. While the importance of NQE has been widely acknowledged, yet we do not have a fully reliable method to account for NQE in the MD thermal conductivity calculations. In this work, we will investigate and analyze the performances of a number of path-integral-based quantum MD methods, using ordered ice as a test case. To establish the validity of these methods, we will compare the MD results with the lattice dynamics results, in both classical and quantum limits. Through such a comparison, we will show that methods such as ring polymer MD stand as a good approach for a complex solid with short phonon lifetimes but could be problematic when describing long-living acoustic phonons. In addition, we will show that the rigid water model, which is the state-of-the-art model in the studies of ice/water systems, fails to capture most of the NQEs in ice thermal conductivity. Neglecting librational and translational NQEs leads to essential errors, which clearly demonstrates the importance of a true quantum simulation method that treats all modes at a consistent quantum level.

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捕获分子动力学中的核量子效应以进行晶格热导率计算：以冰为例

分子动力学（MD）是一种功能强大（也是最可行的工具），可用于计算固体无序材料的热导率。但是，传统的经典MD无法描述核量子效应（NQE），因此对于低温下的轻质材料可能给出不准确的结果。尽管NQE的重要性已得到广泛认可，但我们还没有一种完全可靠的方法来在MD热导率计算中考虑NQE。在这项工作中，我们将使用有序冰作为测试案例，研究和分析许多基于路径积分的量子MD方法的性能。为了确定这些方法的有效性，我们将在经典和量子极限下将MD结果与晶格动力学结果进行比较。通过这样的比较，我们将证明，对于具有短声子寿命的复杂固体，环状聚合物MD等方法是一种很好的方法，但是在描述长寿命声子时可能会出现问题。另外，我们将显示刚性水模型（它是冰/水系统研究中的最新模型）无法捕获冰热导率中的大多数NQE。忽略自由的和平移的NQE会导致本质上的错误，这清楚地证明了一种真正的量子模拟方法的重要性，该方法可以在一致的量子水平上处理所有模式。无法捕获大多数NQE的冰热导率。忽略自由的和平移的NQE会导致本质上的错误，这清楚地证明了一种真正的量子模拟方法的重要性，该方法可以在一致的量子水平上处理所有模式。无法捕获大多数NQE的冰热导率。忽略自由的和平移的NQE会导致本质上的错误，这清楚地证明了一种真正的量子模拟方法的重要性，该方法可以在一致的量子水平上处理所有模式。