用灵活生成的自回归模型,高效预测材料相变与热力学性质。
Scaling Autoregressive Models for Lattice Thermodynamics
- 采用任意顺序生成机制,突破固定序列限制。
- 在20×20伊辛模型和CuAu合金上实现更准自由能计算。
- 适合材料设计、催化等需要大规模热力学模拟的研究者。
预测材料在真实条件下的行为需理解晶格原子构型的统计分布,这对合金设计、催化及相变研究至关重要。传统蒙特卡洛采样在相变附近收敛慢且存在临界减速问题,促使生成模型直接学习热力学分布。现有自回归模型(ARMs)按固定顺序生成,内存与训练成本高,难以应用于真实系统。本文提出结合任意顺序ARMs与边缘化模型(MAMs)的框架:前者可任意条件化部分晶格点生成,后者单次前向传播即可近似任意部分构型的概率,显著降低内存需求。该框架使小晶格训练模型可复用于大系统采样,支持具有晶格感知位置编码的表达性强Transformer架构,计算成本可控。实验表明,基于Transformer的任意顺序MAM在二维伊辛模型和CuAu合金上比多层感知机基ARMs更准确地预测自由能,忠实捕捉相变与临界行为。整体框架实现从10×10到20×20伊辛系统、2×2×4到4×4×8 CuAu超胞的扩展,相比传统方法计算成本更低。
原文摘要 · Abstract (English)
Predicting how materials behave under realistic conditions requires understanding the statistical distribution of atomic configurations on crystal lattices, a problem central to alloy design, catalysis, and the study of phase transitions. Traditional Markov-chain Monte Carlo sampling suffers from slow convergence and critical slowing down near phase transitions, motivating the use of generative models that directly learn the thermodynamic distribution. Existing autoregressive models (ARMs), however, generate configurations in a fixed sequential order and incur high memory and training costs, limiting their applicability to realistic systems. Here, we develop a framework combining any-order ARMs, which generate configurations flexibly by conditioning on any known subset of lattice sites, with marginalization models (MAMs), which approximate the probability of any partial configuration in a single forward pass and substantially reduce memory requirements. This combination enables models trained on smaller lattices to be reused for sampling larger systems, while supporting expressive Transformer architectures with lattice-aware positional encodings at manageable computational cost. We demonstrate that Transformer-based any-order MAMs achieve more accurate free energies than multilayer perceptron-based ARMs on both the two-dimensional Ising model and CuAu alloys, faithfully capturing phase transitions and critical behavior. Overall, our framework scales from $10 \times 10$ to $20 \times 20$ Ising systems and from $2 \times 2 \times 4$ to $4 \times 4 \times 8$ CuAu supercells at reduced computational cost compared to conventional sampling methods.
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