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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Performance of M06, M06-2X, and M06-HF Density Functionals for Conformationally Flexible Anionic Clusters: M06 Functionals Perform Better than B3LYP for a Model System with Dispersion and Ionic Hydrogen-Bonding Interactions
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Performance of M06, M06-2X, and M06-HF Density Functionals for Conformationally Flexible Anionic Clusters: M06 Functionals Perform Better than B3LYP for a Model System with Dispersion and Ionic Hydrogen-Bonding Interactions

机译：M06，M06-2X和M06-HF密度官能团在结构柔性阴离子簇上的性能：对于具有分散和离子氢键相互作用的模型系统，M06官能团的性能优于B3LYP

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We present a comparative assessment of the performance of the M06 suite of density functionals (M06, M06-2X, and M06-HF) against an MP2 benchmark for calculating the relative energies and geometric structures of the Cl~?·arginine and Br~?·arginine halide ion?amino acid clusters. Additional results are presented for the popular B3LYP density functional. The Cl~?·arginine and Br~?·arginine complexes are important prototypes for the phenomenon of anion-induced zwitterion formation. Results are presented for the canonical (noncharge separated) and zwitterionic (charge separated) tautomers of the clusters, as well as the numerous conformational isomers of the clusters. We find that all of the M06 functions perform well in terms of predicting the general trends in the conformer relative energies and identifying the global minimum conformer. This is in contrast to the B3LYP functional, which performed significantly less well for the canonical tautomers of the clusters where dispersion interactions contribute more significantly to the conformer energetics. We find that the M06 functional gave the lowest mean unsigned error for the relative energies of the canonical conformers (2.10 and 2.36 kJ/ mol for Br~?·arginine and Cl~?·arginine), while M06-2X gave the lowest mean unsigned error for the zwitterionic conformers (0.85 and 1.23 kJ/mol for Br?·arginine and Cl~?·arginine), thus providing insight into the types of physical systems where each of these functionals should perform best.
机译：我们提供了针对MP2基准的M06密度泛函套件（M06，M06-2X和M06-HF）的性能的比较评估，该基准用于计算Cl〜？·精氨酸和Br〜？的相对能量和几何结构。 ·精氨酸卤化物离子？氨基酸簇。流行的B3LYP密度泛函还提供了其他结果。 Cl-精氨酸和Br-精氨酸复合物是阴离子诱导的两性离子形成现象的重要原型。给出了簇的正则互变异构体（不带电荷分离）和两性离子互变异构体（电荷分离）的结果，以及簇的众多构象异构体。我们发现，所有M06功能在预测随形调节器相对能量的总体趋势以及确定全局最小随形调节器方面均表现良好。这与B3LYP功能相反，后者对簇的规范互变异构体表现差强人意，其中分散相互作用对构象异构体的能量贡献更大。我们发现，对于标准构象构子的相对能量，M06官能团给出的平均无符号误差最低（对于Br〜？精氨酸和Cl〜？·精氨酸，相对能量为2.10和2.36 kJ / mol），而M06-2X给出的最低平均无符号误差两性离子构象异构体的误差（Br +精氨酸和Cl-α-精氨酸为0.85和1.23 kJ / mol），从而提供了对其中每种功能应发挥最佳作用的物理系统类型的认识。

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