用神经算子直接学习基组密度泛函理论中的势-密度映射,实现线性扩展的量子计算。
Learning the Kohn-Sham map with neural operators for quasi-linear scaling density functional theory

- 以势到密度的映射为学习目标,绕过传统轨道对角化步骤
- 单个模型在8504个分子和固体上训练后,可推广至有机物、绝缘体和金属
- 首次在无轨道构造下实现跨体系收敛,支持超大体系单卡计算
Kohn--Sham密度泛函理论(DFT)是电子结构模拟的基础,但反复的轨道对角化导致计算复杂度为立方级,限制了量子计算的规模。消除辅助轨道同时保持Kohn--Sham精度是无轨密度泛函理论的核心目标,但以往分析与机器学习方法均未成功。现有方法或学习变分动能泛函(数值不稳定),或直接预测基态(外推能力差)。本文提出以Kohn--Sham映射为学习目标:将势直接映射到密度与非相互作用动能,替代轨道对角化过程。本工作聚焦密度预测,采用域不变的SE(3)等变傅里叶神经算子,在实空间网格上从势输入学习密度,实现稳定的准线性标度自洽场迭代。模型联合训练于8,504个分子与固体,单一模型即可泛化至分布外的有机分子、绝缘体与金属。首次实现无需显式构建轨道即可在各类体系中收敛自洽场,且密度、电子谱与结构可观测量达到Kohn--Sham DFT精度。线性标度自洽场还使得单张GPU即可收敛含82,500个价电子的镁位错密度系统。
原文摘要 · Abstract (English)
Kohn--Sham density functional theory (DFT) underpins electronic-structure simulations, but repeated orbital diagonalizations lead to cubic scaling, restricting quantum calculations to modest scales only. Eliminating these auxiliary orbitals while retaining Kohn--Sham accuracy is the central goal of orbital-free DFT, but both analytical and machine-learning methods have so far fallen short. Prior learning approaches either try to learn the variational kinetic-energy functionals, which are ill-conditioned, or directly predict the ground state, which extrapolate poorly to larger systems. Instead, we identify the Kohn--Sham map as the right learning target for orbital-free DFT. It maps a Kohn--Sham potential directly to the corresponding density and noninteracting kinetic energy, quantities otherwise obtained through an orbital diagonalization. Focusing on the density component in this work, a domain-invariant $\mathrm{SE}(3)$-equivariant Fourier neural operator learns to predict it from the potential as input on real-space grids, enabling stable quasi-linear scaling SCFs. Trained jointly on 8,504 molecules and solids, a single model generalizes to out-of-distribution organic molecules, insulators, and metals. For the first time, the same method converges SCFs across these systems without explicitly constructing Kohn--Sham orbitals, while reproducing densities, electronic spectra, and structural observables at Kohn--Sham DFT accuracy. Linear-scaling SCFs additionally allow converging magnesium dislocation densities containing up to 82,500 valence electrons on a single GPU.
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