Kepp Kasper P
DTU Chemistry, Technical University of Denmark , Building 206, 2800 Kongens Lyngby, Denmark.
J Phys Chem A. 2017 Mar 9;121(9):2022-2034. doi: 10.1021/acs.jpca.6b12086. Epub 2017 Feb 24.
Gold plays a major role in nanochemistry, catalysis, and electrochemistry. Accordingly, hundreds of studies apply density functionals to study chemical bonding with gold, yet there is no systematic attempt to assess the accuracy of these methods applied to gold. This paper reports a benchmark against 51 experimental bond enthalpies of AuX systems and seven additional polyatomic and cationic molecules. Twelve density functionals were tested, covering meta functionals, hybrids with variable HF exchange, double-hybrid, dispersion-corrected, and nonhybrid GGA functionals. The defined benchmark data set probes all types of bonding to gold from very electronegative halides that force Au electronic structure, via covalently bonded systems, hard and soft Lewis acids and bases that either work against or complement the softness of gold, the Au molecule probing gold's bond with itself, and weak bonds between gold and noble gases. Zero-point vibrational corrections are relatively small for Au-X bonds, ∼ 11-12 kJ/mol except for Au-H bonds. Dispersion typically provides ∼5 kJ/mol of the total bond enthalpy but grows with system size and is 10 kJ/mol for AuXe and AuKr. HF exchange and LYP correlation produce weaker bonds to gold. Most functionals provide similar trend accuracy, though somewhat lower for M06 and M06L, but very different numerical accuracy. Notably, PBE and TPSS functionals with dispersion display the smallest numerical errors and very small mean signed errors (0-6 kJ/mol), i.e. no bias toward over- or under-binding. Errors are evenly distributed versus atomic number, suggesting that relativistic effects are treated fairly; the mean absolute error is almost halved from B3LYP (45 kJ/mol) to TPSS and PBE (23 kJ/mol, including difficult cases); 23 kJ/mol is quite respectable considering the diverse bonds to gold and the complication of relativistic effects. Thus, studies that use DFT with effective core potentials for gold chemistry, with no alternative due to computational cost, are on solid ground using TPSS-D3 or PBE-D3.
金在纳米化学、催化和电化学中发挥着重要作用。因此，数以百计的研究应用密度泛函来研究与金的化学键合，但尚未有系统的尝试来评估这些应用于金的方法的准确性。本文报告了一项针对51个AuX体系以及另外7个多原子和阳离子分子的实验键焓的基准测试。测试了12种密度泛函，涵盖元泛函、具有可变HF交换的杂化泛函、双杂化泛函、色散校正泛函和非杂化GGA泛函。定义的基准数据集探究了与金的各种类型的键合，从迫使金电子结构的电负性很强的卤化物，到共价键合体系、软硬路易斯酸碱（它们要么与金的软度相反，要么与之互补）、探测金自身键合的金分子，以及金与稀有气体之间的弱键。除了Au - H键外，Au - X键的零点振动校正相对较小，约为11 - 12 kJ/mol。色散通常提供约5 kJ/mol的总键焓，但会随着体系大小而增加，对于AuXe和AuKr为10 kJ/mol。HF交换和LYP相关产生与金较弱的键。大多数泛函提供相似的趋势准确性，但M06和M06L的准确性略低，不过数值准确性差异很大。值得注意的是，带有色散的PBE和TPSS泛函显示出最小的数值误差和非常小的平均符号误差（0 - 6 kJ/mol），即不存在过度或不足键合的偏差。误差相对于原子序数均匀分布，表明相对论效应得到了合理处理；平均绝对误差从B3LYP（45 kJ/mol）到TPSS和PBE（23 kJ/mol，包括困难情况）几乎减半；考虑到与金的各种键合以及相对论效应的复杂性，23 kJ/mol是相当可观的。因此，由于计算成本而别无选择，在金化学研究中使用带有有效核势的密度泛函理论时，使用TPSS - D3或PBE - D3是可靠的。
