Letterman Roger G, DeYonker Nathan J, Burkey Theodore J, Webster Charles Edwin
Department of Chemistry and Computational Research on Materials Institute, The University of Memphis , Memphis, Tennessee 38152, United States.
Department of Chemistry and Center for Computational Sciences, Mississippi State University , Mississippi State, Mississippi 39762-9573, United States.
J Phys Chem A. 2016 Dec 22;120(50):9982-9997. doi: 10.1021/acs.jpca.6b09278. Epub 2016 Dec 12.
Acquisition of highly accurate energetic data for chromium-containing molecules and various chromium carbonyl complexes is a major step toward calibrating bond energies and thermal isomerization energies from mechanisms for Cr-centered photochromic materials being developed in our laboratories. The performance of six density functionals in conjunction with seven basis sets, utilizing Gaussian-type orbitals, has been evaluated for the calculation of gas-phase enthalpies of formation and enthalpies of reaction at 298.15 K on various chromium-containing systems. Nineteen molecules were examined: Cr(CO), Cr(CO), Cr(CO)(CH), Cr(CO)(CClH), Cr(CO)(cis-(CClH)), Cr(CO)(gem-(CClH)), Cr(CO)(trans-(CClH)), Cr(CO)(CClH), Cr(CO)(CCl), CrO, CrF, CrCl, CrCl, CrBr, CrBr, CrOCl, CrOCl, CrOF, and CrOF. The performance of 69 density functionals in conjunction with a single basis set utilizing Slater-type orbitals (STO) and a zeroth-order relativistic approximation was also evaluated for the same test set. Values derived from density functional theory were compared to experimental values where available, or values derived from the correlation consistent composite approach (ccCA). When all reactions were considered, the functionals that exhibited the smallest mean absolute deviations (MADs, in kcal mol) from ccCA-derived values were B97-1 (6.9), VS98 (9.0), and KCIS (9.4) in conjunction with quadruple-ζ STO basis sets and B97-1 (9.3) in conjunction with cc-pVTZ basis sets. When considering only the set of gas-phase reaction enthalpies (ΔH°), the functional that exhibited the smallest MADs from ccCA-derived values were B97-1 in conjunction with cc-pVTZ basis sets (9.1) and PBEPBE in conjunction with polarized valence triple-ζ basis set/effective core potential combination for Cr and augmented and multiple polarized triple-ζ Pople style basis sets (9.5). Also of interest, certainly because of known cancellation of errors, PBEPBE with the least-computationally expensive basis set combination considered in the present study (valence double-ζ basis set/effective core potential combination for Cr and singly-polarized double-ζ Pople style basis sets) also provided reasonable accuracy (11.1). An increase in basis set size was found to have an improvement in accuracy for the best performing functional (B97-1).
获取含铬分子和各种羰基铬配合物的高精度能量数据，是朝着校准我们实验室正在研发的以铬为中心的光致变色材料的键能和热异构化能迈出的重要一步。利用高斯型轨道，评估了六种密度泛函与七种基组结合时，在298.15 K下对各种含铬体系的气相生成焓和反应焓的计算性能。研究了19个分子：Cr(CO)、Cr(CO)、Cr(CO)(CH)、Cr(CO)(CClH)、Cr(CO)(顺式-(CClH))、Cr(CO)(偕式-(CClH))、Cr(CO)(反式-(CClH))、Cr(CO)(CClH)、Cr(CO)(CCl)、CrO、CrF、CrCl、CrCl、CrBr、CrBr、CrOCl、CrOCl、CrOF和CrOF。还针对同一测试集评估了69种密度泛函与利用斯莱特型轨道（STO）和零阶相对论近似的单个基组结合时的性能。将密度泛函理论得出的值与可获得的实验值或从相关一致复合方法（ccCA）得出的值进行了比较。当考虑所有反应时，与ccCA得出的值表现出最小平均绝对偏差（MAD，单位为kcal/mol）的泛函是与四重ζ STO基组结合的B97-1（6.9）、VS98（9.0）和KCIS（9.4），以及与cc-pVTZ基组结合的B97-1（9.3）。仅考虑气相反应焓（ΔH°）集时，与ccCA得出的值表现出最小MAD的泛函是与cc-pVTZ基组结合的B97-1（9.1），以及与用于Cr的极化价三重ζ基组/有效核势组合以及增强和多重极化三重ζ波普尔型基组结合的PBEPBE（9.5）。同样值得注意的是，肯定是由于已知的误差抵消，本研究中考虑的计算成本最低的基组组合（用于Cr的价双ζ基组/有效核势组合以及单极化双ζ波普尔型基组）的PBEPBE也提供了合理的精度（11.1）。发现对于表现最佳的泛函（B97-1），基组大小的增加会提高精度。
