用机器学习密度预测分子电子结构,实现高精度光谱模拟。
Enhancing molecular dynamics with equivariant machine-learned densities

- 以电子密度为学习核心,构建基于SE(3)等变神经网络的密度预测模型。
- 在乙醇、硫醇等分子上生成的红外光谱与实验高度吻合,12单体聚噻吩链也稳定可运行。
- 适合需要精准电子性质和光谱预测的大规模分子动力学研究者。
机器学习原子间势(MLIPs)已实现接近从头算精度的分子动力学模拟,但受限于仅能预测能量和力,无法获取偶极矩、极化率等电子可观测量。本文提出DenSNet,一种以密度为先的机器学习电子结构方法,直接学习核构型到基态电子密度的霍亨伯格-科恩映射。模型采用SE(3)等变神经网络预测灵活的原子中心高斯基组密度系数,并引入Δ-学习策略,利用叠加原子密度作为先验加速训练。第二个等变网络将预测密度映射到总能量,形成统一的动力学与电子结构框架。在乙醇、乙硫醇和间苯二酚上的验证显示,机器学习轨迹的红外光谱与实验气体相测量高度一致。为测试扩展性,在含1–6个单体的聚噻吩寡聚物上训练,并外推至最多12个单体的链,生成的长时间轨迹红外光谱与参考密度泛函理论计算吻合。本工作表明,将电子密度重新确立为学习核心,为大规模分子模拟中可迁移的光谱与电子性质预测提供了可行路径。
原文摘要 · Abstract (English)
Machine-learning interatomic potentials (MLIPs) have enabled molecular dynamics at near ab initio accuracy, yet remain limited to energies and forces by construction, leaving electronic observables such as dipole moments and polarizabilities inaccessible. We introduce DenSNet, a density-first approach to machine-learned electronic structure that learns the Hohenberg--Kohn map from nuclear configurations to the ground-state electron density. Our approach employs an SE(3)-equivariant neural network to predict density coefficients of a flexible atom-centered Gaussian basis, combined with a $Δ$-learning strategy that uses superposed atomic densities as a prior to accelerate training. A second equivariant network then maps the predicted density to the total energy, providing a unified framework for molecular dynamics and electronic structure. We validate DenSNet on ethanol, ethanethiol, and resorcinol, where infrared spectra from machine-learned trajectories show excellent agreement with experimental gas-phase measurements. To test scalability, we train on polythiophene oligomers with 1--6 monomers and extrapolate to chains of up to 12 monomers, generating stable long-time trajectories whose infrared spectra agree with reference density functional theory calculations. Here, we show that reinstating the electron density as the central learned quantity opens a practical route to transferable prediction of spectroscopic and electronic observables in large-scale molecular simulations.
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