AI 中文总结
研究尖晶石化合物相关性质，通过从材料项目挑选条目训练树集成替代模型预测多种性质，经多次分组留出法测试，冠军模型在形成能等方面有一定误差水平，带隙回归有负面结果，还通过SHAP归因等分析了模型与性质的联系。
AI 中文摘要
我们从材料项目中挑选了320个立方（$Fd\bar{3}m$）尖晶石条目，包括氮化物、氧化物、硫化物和硒化物，以及单阳离子混合价$A_3X_4$化合物，并训练了树集成替代模型来预测形成能、凸包以上能量、带隙、总磁化强度和金属性。根据CrystalNN配位数将阳离子分为四面体状和八面体状组，评估过程中始终考虑组的因素。通过二十多次重复分组留出法测试，冠军模型在形成能、凸包距离和磁化强度等方面达到了一定的平均绝对误差，金属性准确率也较高。在带隙回归方面，在配对自展测试下，19个非金属样本的测试中未超过简单基线。SHAP归因将磁化模型与八面体$d$占有率联系起来，将形成能和带隙模型与电负性描述符联系起来。
英文摘要
We curated 320 cubic ($Fd\bar{3}m$) spinel entries from the Materials Project-nitrides, oxides, sulfides, and selenides, including single-cation mixed-valence $A_3X_4$ compounds-and trained tree-ensemble surrogates for the formation energy, energy above the convex hull, band gap, total magnetization, and metallicity. Cations were assigned to tetrahedral-like and octahedral-like groups from CrystalNN coordination numbers rather than from element identity, and the evaluation was group-aware throughout: splits were grouped by reduced formula, every transform was fit on training folds only, and champion models were selected on cross-validated scores before the holdout was examined. Over twenty repeated grouped holdouts (single-seed refits that reuse the tuned hyperparameters, and are therefore mildly optimistic) the champions reach mean absolute errors of $0.121\pm0.030$ eV/atom for the formation energy, $0.048\pm0.013$ eV/atom for the hull distance, and $1.27\pm0.19$~\muBfu{} for the magnetization, with a metallicity accuracy of $0.85\pm0.06$. Band-gap regression does not beat a trivial baseline on the 19-member non-metal holdout under paired bootstrap testing, we report this negative result and trace it to sample scarcity and to the semi-local DFT labels. On the identical grouped split, the tabular champion is more accurate than an untuned MEGNet trained from scratch (0.087 versus 0.209 eV/atom formation-energy MAE on the primary holdout), a comparison that bounds, rather than settles, the descriptor-versus-graph question at this data scale. SHAP attribution ties the magnetization model to octahedral $d$-occupancy and the formation-energy and band-gap models to electronegativity descriptors, and grouped conformal intervals, permutation nulls, and leave-one-chemistry-out tests bound a domain of applicability that is uneven across anions and cations.
