AI 中文总结
该研究提出杂阴离子材料可通过两种阴离子有序排列产生结构手性，以NbO₂F为例，DFT和蒙特卡罗模拟验证其存在平衡手性相，为新型手性功能材料提供候选。
AI 中文摘要
无机晶体中结构手性的现有形成途径依赖于非手性母体结构的对称性降低原子位移。我们证明，手性也可由两种阴离子在非手性母体位点上的有序排列强制产生，与原子位移无关。具有2:1阴离子化学计量比的ReO₃型氧氟化物（如NbO₂F）表现出两种有序模式：顺式八面体配位和周期三阴离子链有序，两者均源于d⁰阳离子的偏心。通过直接枚举，我们证明最小公度晶胞上结合两种有序的所有构型均为手性，属于Sohncke空间群。针对NbO₂F的具体情况，密度泛函理论（DFT）计算预测基态为最大对称手性构型；对DFT训练的集团展开模型进行Wang-Landau蒙特卡罗模拟，预测在494 K的一级相变前存在平衡手性相。这些结果确立了构型有序是化学可实现的结构手性形成途径，并标志着具有类似有序化学的杂阴离子材料是新型手性功能材料的候选者。
英文摘要
Established routes to structural chirality in inorganic crystals depend on symmetry-lowering atomic displacements of an achiral parent structure. We show that chirality can instead be forced by the ordering of two anion species over the sites of an achiral parent, independent of atomic displacements. ReO$_3$-type oxyfluorides with a 2:1 anion stoichiometry, such as NbO$_2$F, exhibit two ordering patterns: cis octahedral coordination and period-three anion-chain ordering, both rooted in the off-centring of $d^0$ cations. By direct enumeration, we prove that every configuration combining both orderings on the smallest commensurate cell is chiral, belonging to a Sohncke space group. For the specific case of NbO$_2$F, density-functional theory calculations predict that the ground state is the maximally symmetric chiral configuration. Wang-Landau Monte Carlo simulations of a DFT-trained cluster-expansion model predict an equilibrium chiral phase up to a first-order transition at 494 K. These results establish configurational ordering as a chemically realisable route to structural chirality, and mark heteroanionic materials with analogous ordering chemistry as candidates for a new class of chiral functional materials.
