M_6^(0,±)(M=Os,Ir,Pt)团簇结构与性质的密度泛函理论研究

Density functional theory study on the structure and properties of M_6^(0,±)(M=Os,Ir,Pt) clusters

采用密度泛函理论(DFT)中的杂化密度泛函(B3LYP)方法,在LANL2DZ基组水平上对M06,±(M=Os,Ir,Pt)团簇的各种可能构型进行了几何结构优化,得出各团簇的最稳定构型,并对其能量、振动频率、热力学性质、核独立化学位移(NICS)和极化率进行了理论研究.结果表明,M06,±(M=Os,Ir)团簇的基态都是三棱柱结构,Pt-6团簇的基态是平面三角形结构;M06,±(M=Os,Ir,Pt)团簇生成焓都为负值,热力学上是稳定的;NICS值都为负值,表明M06,±(M=Os,Ir,Pt)团簇都具有芳香性,其中Os-6团簇的芳香性最强;从光谱分析来看,Os6的IR和Raman谱的较强吸收峰的个数最多,Ir6的IR和Raman谱的最强吸收峰都只有一个,IR最强吸收峰在137.0和143.5 cm-1之间,Raman谱最强的吸收峰位于169.5 cm-1处;Pt6的IR和Raman谱的最强吸收峰分别位于50.2和194.7 cm-1处.

All the possible geometrical structures of M6^0,±（M = Os, Ir, Pt） clusters are optimized with a hybrid density functional theory （B3LYP） at LANL2DZ level. For the most stable structures, the energy, vibration frequencies, thermodynamic properties,Nucleus Independent Chemical Shifts （NICS） and polarizability are analyzed. It is shown that the ground state structures of M6^0,±（M = Os, Ir） are tri-prism, the anion Pt6 cluster is plane triangle. From the point of view of thermodynamics, M6^0,± （M = Os, Ir, Pt） clusters are stable because of the negative enthalpy of formation. The negative NICS of M6^0,±（M = Os, Ir, Pt） clusters show aromaticity, and the aromaticity of Os6^- is the strongest, the number of IR and Raman absorption peaks of Os6 is the most, the IR absorption peak of Ir6 locates between 137.0 and 143.5 cm^-1 ,the Raman locates at 169.5 cm^-1 ,the IR and Raman absorption peak of Pt6 are located at 50.2 and 194.7 cm^-1 respectively.