arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2012.15222physics.chem-phcond-mat.mtrl-sci
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机器学习增强的原子尺度结构全局优化

Global optimization of atomistic structure enhanced by machine learning

Malthe K. Bisbo, Bjørk Hammer

AI总结:

本文提出GOFEE全局优化方法的两项改进:基于DFT低能结构聚类的种群生成和第一性原理内连续弛豫路径的最终利用步骤,并在碳团簇体系中验证了其通用性。

摘要:

基于第一性原理能量表达式的全局优化(GOFEE)是一种在计算代价高昂的能量景观中识别低能结构的高效方法,这类能量景观包括密度泛函理论(DFT)、支持范德华力的DFT,甚至DFT之外的方法所描述的能量景观。GOFEE依赖一个在运行中即时训练的机器学习能量与力的代理模型来探索构型空间,从而无需对所有候选结构使用第一性原理方法进行昂贵的弛豫。在本文中,我们详细阐述了在高斯过程回归(GPR)代理模型中使用具有两个长度尺度的高斯核的重要性。我们进一步探讨了在GOFEE中使用下置信界进行候选结构弛豫与选择的作用。此外,我们提出了对该方法的两项改进:1)种群生成现在依赖于对所有经DFT评估的低能结构进行聚类,每个聚类中能量最低的成员构成种群。2)在能量景观中已被充分采样的盆地内进行的最终弛豫,即最终的利用步骤,现在改为在第一性原理方法内部以连续弛豫路径的方式执行,从而允许对最佳结构进行任意精细的弛豫,而不受代理模型预测分辨率的限制。通过将GOFEE方法应用于识别气相富勒烯型24原子碳团簇以及负载在Ir(111)上的穹顶形18原子碳团簇的低能结构,展示了该方法的通用性。

英文摘要:

Global Optimization with First-principles Energy Expressions (GOFEE) is an efficient method for identifying low energy structures in computationally expensive energy landscapes such as the ones described by density functional theory (DFT), van der Waals-enabled DFT, or even methods beyond DFT. GOFEE relies on a machine learned surrogate model of energies and forces, trained on-the-fly, to explore configuration space, eliminating the need for expensive relaxations of all candidate structures using first-principles methods. In this paper we elaborate on the importance of the use of a Gaussian kernel with two length scales in the Gaussian Process Regression (GPR) surrogate model. We further explore the role of the use in GOFEE of the lower confidence bound for relaxation and selection of candidate structures. In addition, we present two improvements to the method: 1) the population generation now relies on a clustering of all low-energy structures evaluated with DFT, with the lowest energy member of each cluster making up the population. 2) the very final relaxations in well-sampled basins of the energy landscape, the final exploitation steps, are now performed as continued relaxation paths within the first-principles method, to allow for arbitrarily fine relaxations of the best structures, independently of the predictive resolution of the surrogate model. The versatility of the GOFEE method is demonstrated by applying it to identify the low-energy structures of gas-phase fullerene-type 24-atom carbon clusters and of dome-shaped 18-atom carbon clusters supported on Ir(111).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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