论文标题
通过过渡金属簇对C $ -H键激活甲烷的理论见解：Anharmonic效应的作用
Theoretical Insights into C$-$H Bond Activation of Methane by Transition Metal Clusters: The Role of Anharmonic Effects
论文作者
论文摘要
针对甲烷激活的材料设计，我们研究温度（$ t $），压力（$ p $）的依赖性，使用具有广泛应用的原型模型催化剂在反应性大气中的组成，结构和稳定性：在组合氧气和甲烷氛围中的游离过渡金属（Ni）簇。采用了一种强大的方法论方法，以表明常规的谐波近似对这类材料的失败失败，并捕获对振动自由能贡献的非谐作用是必不可少的。为了将非谐度纳入振动自由能中，我们通过热力学积分方法与杂化密度功能理论和{\ em ab sible}分子动力学模拟输入评估簇的过量自由能。我们发现，非谐作用在检测C $ -H债券的激活方面具有重大影响，而由于振动模式的错误预测，谐波红外光谱完全失败。
Aiming towards materials design for methane activation, we study temperature ($T$), pressure ($p$) dependence of the composition, structure, and stability of metal oxide clusters in a reactive atmosphere using a prototypical model catalyst having wide applications: free transition metal (Ni) clusters in a combined oxygen and methane atmosphere. A robust methodological approach is employed, to show that the conventional harmonic approximation miserably fails for this class of materials and capturing anharmonic effects to the vibration free energy contribution is indispensable. To incorporate the anharmonicity in the vibrational free energy, we evaluate the excess free energy of the clusters numerically by thermodynamic integration method with hybrid density functional theory and {\em ab initio} molecular dynamics simulation inputs. We find that the anharmonic effect has a significant impact in detecting the activation of C$-$H bond, whereas the harmonic infrared spectrum completely fails due to the wrong prediction of the vibrational modes.
