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arXiv 2109.06282cond-mat.mtrl-sci
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氧化锆的相变:超越密度泛函理论的机器学习力场

Phase Transitions of Zirconia: Machine-Learned Force Fields Beyond Density Functional Theory

Peitao Liu, Carla Verdi, Ferenc Karsai, Georg Kresse

摘要:

我们提出了一种方法来产生机器学习力场(MLFF)与超越密度泛函理论(DFT)的准确性。我们的方法结合了动态主动学习和$Δ$ -机器学习,以便基于随机相位近似(RPA)生成氧化锆的MLFF。具体地,在基于DFT的分子动力学模拟期间实时训练的MLFF由另一个MLFF校正,该另一个MLFF在RPA和DFT计算的能量、力和应力张量之间的差异上训练。由于差异的相对平滑的性质,仅在小单位单元的少量代表性结构上执行昂贵的RPA计算。这些结构是由具有低空间分辨率的核矩阵的奇异值分解秩压缩确定的。这大大降低了计算成本,使我们能够生成一个MLFF完全能够再现高层次的量子力学计算超越DFT。我们仔细验证我们的方法,并证明其成功地研究氧化锆的相变。

英文摘要:

We present an approach to generate machine-learned force fields (MLFF) with beyond density functional theory (DFT) accuracy. Our approach combines on-the-fly active learning and $Δ$-machine learning in order to generate an MLFF for zirconia based on the random phase approximation (RPA). Specifically, an MLFF trained on-the-fly during DFT based molecular dynamics simulations is corrected by another MLFF that is trained on the differences between RPA and DFT calculated energies, forces and stress tensors. Thanks to the relatively smooth nature of the differences, the expensive RPA calculations are performed only on a small number of representative structures of small unit cells. These structures are determined by a singular value decomposition rank compression of the kernel matrix with low spatial resolution. This dramatically reduces the computational cost and allows us to generate an MLFF fully capable of reproducing high-level quantum-mechanical calculations beyond DFT. We carefully validate our approach and demonstrate its success in studying the phase transitions of zirconia.

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