An Efficient Way to Model Complex Iron Carbides: A Benchmark Study of DFTB2 against DFT
An Efficient Way to Model Complex Iron Carbides: A Benchmark Study of DFTB2 against DFT
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DOI：
10.1021/acs.jpca.2c06805
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发表时间：
2023-02-27
影响因子：
2.9
通讯作者：
Wen, Xiaodong
中科院分区：
文献类型：
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作者：
Bai, Jiawei;Liu, Xingchen;Wen, Xiaodong
近年来，由于其在催化领域的巨大潜力，如费托合成和碳纳米管的生长，碳化铁引起了越来越多的关注。理论计算可以在原子尺度上提供对这些反应的更透彻的理解。然而，由于在operando条件下的活性相和表面结构的碳化铁的极端复杂性，基于密度泛函理论（DFT）的计算是太昂贵的实际大模型的碳化铁颗粒。因此，需要一种廉价、高效、精度可与DFT相媲美的量子力学模拟方法。在这项工作中，我们采用自旋极化的自洽电荷密度泛函紧束缚（DFTB 2）的方法，通过重新参数化的排斥部分的Fe-C相互作用的碳化铁。为了评估改进参数的性能，与以前的实验值和DFT方法得到的结果与DFTB 2方法得到的碳化铁块体和团簇的结构和电子性质进行了比较。计算的晶格参数和态密度接近DFT预测。基准测试结果表明，提出的Fe-C相互作用的参数化提供了可转移的和平衡的描述碳化铁系统。因此，自旋极化的DFTB 2被认为是描述碳化铁体系的有效和可靠的方法。
Iron carbides have attracted increasing attention in recent years due to their enormous potential in catalytic fields, such as Fischer-Tropsch synthesis and the growth of carbon nanotubes. Theoretical calculations can provide a more thorough understanding of these reactions at the atomic scale. However, due to the extreme complexity of the active phases and surface structures of iron carbides at the operando conditions, calculations based on density functional theory (DFT) are too costly for realistically large models of iron carbide particles. Therefore, a cheap and efficient quantum mechanical simulation method with accuracy comparable to DFT is desired. In this work, we adopt the spin-polarized self-consistent charge density functional tight-binding (DFTB2) method for iron carbides by reparametrization of the repulsive part of the Fe-C interactions. To assess the performance of the improved parameters, the structural and electronic properties of iron carbide bulks and clusters obtained with DFTB2 method are compared with the previous experimental values and the results obtained with DFT approach. Calculated lattice parameters and density of states are close to DFT predictions. The benchmark results show that the proposed parametrization of Fe-C interactions provides transferable and balanced description of iron carbide systems. Therefore, spin-polarized DFTB2 is valued as an efficient and reliable method for the description of iron carbide systems.