AI 中文总结
该研究以金属有机框架为对象，结合理论计算与光谱实验，发现其声子介电响应可超出传统密度标度，揭示框架拓扑是新的介电自由度。
AI 中文摘要
有效介质理论将材料孔隙率视为被动稀释。通过从头算密度泛函理论和同构沸石咪唑框架的高分辨率同步加速器太赫兹（THz）光谱，研究发现电子介电常数遵循克劳修斯-莫索蒂密度标度，而声子贡献违反传统密度标度规则；相同的玻恩电荷排除了局部化学的作用，框架连通性使THz响应局域化，声子本征矢量的相干性决定模式有效电荷，金属有机框架中普遍存在的长程框架拓扑是超出传统固体密度标度的介电自由度。
英文摘要
Effective-medium theory treats material porosity as passive dilution. Using ab initio density functional theory and high-resolution synchrotron terahertz (THz) spectroscopy on isochemical zeolitic-imidazolate frameworks, we show that while the electronic permittivity obeys Clausius-Mossotti density scaling, the phonon contribution violates the conventional density scaling rules. Identical Born charges rule out the role of local chemistry. Instead, the framework connectivity localizes the THz response, where the coherency of phonon eigenvectors determines the mode-effective charges. Long-range architecture of framework topology ubiquitous in metal-organic frameworks is therefore a dielectric degree of freedom beyond the density scaling of conventional solids.
Comments13 pages, 4 Figures, Supplementary Materials
