PAF64 database

We construct a comprehensive database of CCSD(T) isomerization energies of 64 perfluorinated polycyclic aromatic hydrocarbons (PAFs) and corresponding polycyclic aromatic hydrocarbons (PAHs) using the G4(MP2) composite ab initio method. The considered PAF and PAH compounds are (number of isomers given in parentheses): C₁₂X₈ (2), C₁₄X₁₀ (2), C₁₆X₁₀ (2), C₁₇X₁₂ (11), C₁₈X₁₂ (5), C₁₉X₁₂ (12), C₂₀X₁₂ (21), C₂₁X₁₄ (3), and C₂₂X₁₂ (6) (X = H, F). This database includes a diverse range of structural motifs, including planar and non-planar configurations, and exhibits unique stability trends influenced by steric effects and F•••F repulsion. Perfluorination significantly alters the relative stabilities of the PAH isomers, with some isomer sets exhibiting complete reversals in energetic ordering. We use the G4(MP2) benchmark isomerization energies to evaluate the performance of 35 DFT and 12 dispersion-corrected DFT-D4 methods. We show that the PAF isomerization energies pose a substantial challenge for DFT methods. D4 dispersion corrections are critical for attaining mean absolute deviations (MADs) below the threshold of chemical accuracy (i.e., below 4.2 kJ mol^–1). The best-performing methods from each rung of Jacob’s Ladder are (MADs given in parentheses): BLYP-D4 (4.5), M06-L-D4 (4.8), B3PW91-D4 (3.4), and PW6B95-D4 (3.3 kJ mol^–1). Overall, B3PW91-D4 emerges as the best functional, achieving high accuracy while also successfully predicting the most stable isomers in challenging cases. This study underscores the current limitations of many DFT methods and provides critical guidance for future studies on electron-deficient aromatic systems, including perfluorinated nanomaterials such as graphene derivatives, fullerenes, and carbon nanotubes.本研究采用G4(MP2)复合从头算（ab initio）方法，构建了涵盖64种全氟多环芳烃（perfluorinated polycyclic aromatic hydrocarbons, PAFs）及其对应多环芳烃（polycyclic aromatic hydrocarbons, PAHs）的CCSD(T)异构化能综合数据库。本次研究涉及的PAFs与PAHs化合物通式及对应异构体数目（括号内标注）如下：C₁₂X₈（2种）、C₁₄X₁₀（2种）、C₁₆X₁₀（2种）、C₁₇X₁₂（11种）、C₁₈X₁₂（5种）、C₁₉X₁₂（12种）、C₂₀X₁₂（21种）、C₂₁X₁₄（3种）与C₂₂X₁₂（6种），其中X=H或F。 该数据库包含丰富多样的结构基元，涵盖平面与非平面构型，并展现出受空间位阻效应与F···F排斥作用调控的独特稳定性变化规律。全氟取代会显著改变PAHs异构体的相对稳定性，部分异构体组的能量排序甚至会完全反转。 本研究以G4(MP2)方法得到的基准异构化能为参照，评估了35种密度泛函理论（DFT）方法与12种色散校正DFT-D4方法的性能。研究表明，PAFs的异构化能对DFT方法构成了显著挑战。D4色散校正是将平均绝对偏差（mean absolute deviations, MAD）控制在化学精度阈值（即低于4.2 kJ·mol⁻¹）以内的关键因素。 基于密度泛函“雅各布天梯”（Jacob’s Ladder）各层级的最优表现方法如下（括号内为MAD值）：BLYP-D4（4.5）、M06-L-D4（4.8）、B3PW91-D4（3.4）与PW6B95-D4（3.3 kJ·mol⁻¹）。综合来看，B3PW91-D4为表现最佳的泛函，既实现了高精度，又能在复杂场景中准确预测最稳定的异构体。 本研究阐明了多数DFT方法当前存在的局限性，并为未来针对缺电子芳香体系的研究提供了重要指导，这类体系涵盖石墨烯衍生物、富勒烯与碳纳米管等全氟纳米材料。