Abstract Density functional theory (DFT) based calculations are carried out to study effect of molecular charge on both the binding energy as well as chemical Raman enhancement of deprotonated 4-Mercaptopyridine (ligand) bound to the semiconducting nanocluster, Zn3Se3 and metal substituted nanoclusters, Zn2MSe3 (M: Ag, Cu). Change of molecular charge from 0 to −1 increases binding energy of the ligand for Zn3Se3 cluster and decreases Raman activity of vibrational modes. On the other hand, the ligand bound to the metal substituted nanoclusters, Zn2MSe3 shows minimal decrease in binding energy and a noteworthy enhancement in Raman activity of the vibrational modes, on varying the molecular charge from 0 to −1. Static Raman activities of vibrational modes are analyzed using change of molecular polarizability components with normal coordinates of the modes. An APT (Atomic Polar Tensor) charge based descriptor is used for characterization of the chemical Raman enhancement. The descriptor measures substrate induced charge concentration per unit displacement of an atom involved in a mode of vibration. We also show that significantly enhanced intensity of vibrational modes is associated with atoms of relatively greater magnitudes of the APT charge based descriptor.

中文翻译：

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4-巯基吡啶吸附在半导体纳米团簇上的化学拉曼增强原子级描述的基于APT电荷的描述符：理论研究

摘要 进行了基于密度泛函理论 (DFT) 的计算以研究分子电荷对结合到半导体纳米团簇 Zn3Se3 和金属取代纳米团簇 Zn2MSe3 的去质子化 4-巯基吡啶（配体）的结合能和化学拉曼增强的影响（M：银，铜）。分子电荷从 0 到 -1 的变化增加了配体对 Zn3Se3 簇的结合能并降低了振动模式的拉曼活性。另一方面，与金属取代的纳米团簇结合的配体 Zn2MSe3 在将分子电荷从 0 变化到 -1 时显示出结合能的最小降低和振动模式的拉曼活性显着增强。振动模式的静态拉曼活动是使用分子极化率分量随模式法向坐标的变化来分析的。基于 APT（原子极性张量）电荷的描述符用于表征化学拉曼增强。描述符测量振动模式中原子每单位位移的基板感应电荷浓度。我们还表明，显着增强的振动模式强度与基于 APT 电荷的描述符的相对较大量级的原子相关。