Certain negative thermal expansion (NTE) materials have been reported to exhibit anomalous lattice thermal conductivity (LTC), making them particularly interesting for theoretical studies. In Zn(CN)2 and Cd(CN)2, cyanide bonds have induced great NTE behavior and anharmonicity, making us believe they would exhibit anomalous LTC. To investigate this, we employed first-principles calculations based on density functional theory and solved the linearized Boltzmann transport equation within the relaxation time approximation to calculate the LTC. Our analysis reveals that both Zn(CN)₂ and Cd(CN)₂ have low LTC, with Cd(CN)₂ exhibiting a notably anomalous glass-like behavior. Some phonons with long lifetimes, short mean free paths (MFPs), and strong anharmonicity contribute most to the anomalous LTC observed in both materials. Analysis of the phonon spectral functions and the weighted joint density of states reveals that three-phonon interactions are significant in both materials, impacting their LTCs, particularly in Cd(CN)₂.

中文翻译：

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负热膨胀材料 Zn（CN）2 和 Cd（CN）2 的谐振度和晶格热导率第一性原理计算


据报道，某些负热膨胀 （NTE） 材料表现出异常的晶格热导率 （LTC），这使得它们特别适合理论研究。在 Zn（CN）2 和 Cd（CN）2 中，氰化键诱导了强烈的 NTE 行为和不和谐性，使我们相信它们会表现出异常的 LTC。为了研究这一点，我们采用了基于密度泛函理论的第一性原理计算，并在弛豫时间近似内求解线性玻尔兹曼输运方程来计算 LTC。我们的分析表明，Zn（CN）₂ 和 Cd（CN）₂ 都具有较低的 LTC，其中 Cd（CN）₂ 表现出明显的异常玻璃状行为。一些寿命长、平均自由程短 （MFP） 和强不谐性的声子对在这两种材料中观察到的 LTC 异常贡献最大。对声子谱函数和加权结合态密度的分析表明，三声子相互作用在两种材料中都很重要，影响它们的 LTC，尤其是在 Cd（CN）₂ 中。