Ilawe Niranjan V, Zimmerman Jonathan A, Wong Bryan M
Department of Chemical & Environmental Engineering and Materials Science & Engineering Program, University of California-Riverside , Riverside, California 92521, United States.
Hydrogen and Combustion Technologies Department, Sandia National Laboratories , Livermore, California 94551, United States.
J Chem Theory Comput. 2015 Nov 10;11(11):5426-35. doi: 10.1021/acs.jctc.5b00653. Epub 2015 Oct 13.
Dispersion interactions play a crucial role in noncovalently bound molecular systems, and recent studies have shown that dispersion effects are also critical for accurately describing covalently bound solids. While most studies on bulk solids have solely focused on equilibrium properties (lattice constants, bulk moduli, and cohesive energies), there has been little work on assessing the importance of dispersion effects for solid-state properties far from equilibrium. In this work, we present a detailed analysis of both equilibrium and highly nonequilibrium properties (tensile strengths leading to fracture) of various palladium-hydride systems using representative DFT methods within the LDA, GGA, DFT-D2, DFT-D3, and nonlocal vdw-DFT families. Among the various DFT methods, we surprisingly find that the empirically constructed DFT-D2 functional gives extremely anomalous and qualitatively incorrect results for tensile strengths in palladium-hydride bulk solids. We present a detailed analysis of these effects and discuss the ramifications of using these methods for predicting solid-state properties far from equilibrium. Most importantly, we suggest caution in using DFT-D2 (or other coarse-grained parametrizations obtained from DFT-D2) for computing material properties under large stress/strain loads or for evaluating solid-state properties under extreme structural conditions.
色散相互作用在非共价键合的分子体系中起着至关重要的作用，最近的研究表明，色散效应对于准确描述共价键合的固体也至关重要。虽然大多数关于块状固体的研究仅关注平衡性质（晶格常数、体模量和内聚能），但对于评估色散效应在远离平衡的固态性质中的重要性却几乎没有相关工作。在这项工作中，我们使用LDA、GGA、DFT-D2、DFT-D3和非局域vdw-DFT族中的代表性密度泛函理论（DFT）方法，对各种钯氢体系的平衡和高度非平衡性质（导致断裂的拉伸强度）进行了详细分析。在各种DFT方法中，我们惊讶地发现，经验构建的DFT-D2泛函对于钯氢块状固体的拉伸强度给出了极其异常且定性错误的结果。我们对这些效应进行了详细分析，并讨论了使用这些方法预测远离平衡的固态性质的后果。最重要的是，我们建议在大应力/应变载荷下计算材料性质或在极端结构条件下评估固态性质时，谨慎使用DFT-D2（或从DFT-D2获得的其他粗粒度参数化方法）。
