化学分辨的拓扑坐标连接结构动力学与构型热力学
Chemically Resolved Topological Coordinates Link Structural Dynamics and Configurational Thermodynamics
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中文总结 AI 辅助
该研究构建多分辨率化学导向持续同调方法，以CsPbI₃等为对象，揭示化学网络拓扑连接结构与物理响应的机制，还测试了SchNet等能量模型对DFT构型排序的保留情况。
中文摘要 AI 辅助
原子坐标可确定结构，但无法揭示跨多个长度尺度的化学连通性如何与原子运动及构型能量排序相关联。我们构建了四个分辨率下的化学导向持续同调方法，分别为完整网络、单个位点、空间场及置换排列，同时保留每个连通性特征的化学身份与长度尺度。在500-700 K五个温度下对δ相和γ相CsPbI₃进行的从头算分子动力学（ab initio molecular dynamics, AIMD）轨迹分析显示，角共享的γ相网络具有更低的Pb-I恢复刚度，允许碘离子发生更大位移；然而与边共享的δ相相比，碘离子位置相关性的衰减速度慢2.27倍，且Pb网络拓扑保留记忆的时间长1.63倍。因此，局部柔软性与网络记忆的丧失是两个不同的特性。在单个位点层面，γ相中罕见的具有类δ相Cs笼连通性的Pb环境，会在后续0.5 ps内引发更大0.17 Å的Pb位移。相同的Pb网络坐标可分辨2560原子构成的δ|γ边界处角共享连通性的破坏。在掺杂的CsPbI₃中，紧凑的掺杂剂排列会引发更大的主体协同弛豫，且在密度泛函理论（density-functional-theory, DFT）能量上比相同组成的分散排列更低。具有相当能量误差的SchNet和Allegro模型族沿该坐标编码出相反的排序，在247个提供的模型中，有61个在独立测试结构上的误差低于1 meV atom⁻¹，且反转了DFT的关系。由于相对构型能量决定玻尔兹曼布居，化学网络拓扑将结构与物理响应关联起来，即使学习到的能量模型平均误差很小，也可用于测试其是否保留了DFT的构型排序。
英文摘要
Atomic coordinates specify a structure, but they do not reveal how chemical connectivity across several length scales relates to atomic motion and configurational energy ordering. We formulate chemically directed persistent homology at four resolutions---complete networks, individual sites, spatial fields, and substitutional arrangements---while retaining the chemical identity and length scale of each connectivity feature. In \textit{ab initio} molecular dynamics (AIMD) trajectories of $δ$- and $γ$-CsPbI$_3$ at five temperatures spanning 500--700 K, the corner-sharing $γ$ network has a lower Pb--I restoring stiffness and permits larger iodide excursions, yet iodide positional correlations decay 2.27 times more slowly and Pb-network topology retains memory 1.63 times longer than in the edge-sharing $δ$ phase. Local softness and loss of network memory are therefore distinct. At individual sites, rare $γ$-phase Pb environments with a $δ$-like Cs-cage connectivity precede 0.17 $\mathring{\mathrm{A}}$ greater Pb displacement over the subsequent 0.5 ps. The same Pb-network coordinate resolves disruption of corner-sharing connectivity across a 2560-atom $δ|γ$ boundary. In substituted CsPbI$_3$, compact dopant arrangements undergo greater cooperative host relaxation and lie lower in density-functional-theory (DFT) energy than dispersed arrangements of the same composition. SchNet and Allegro model families with comparable energy errors encode opposite ordering along this coordinate, and 61 of 247 supplied models with errors below 1 meV atom$^{-1}$ on separate test structures reverse the DFT relation. Because relative configurational energies set Boltzmann populations, chemical network topology links structure to physical response and tests whether learned energy models preserve DFT configurational ordering even when their average errors are small.
发表机构
- Indian Institute of Technology Roorkee（印度理工学院罗尔基分校）
机构由 AI 辅助整理，请以论文原文为准。
