Chen Gang, Wang Qian, Sun Qiang, Kawazoe Yoshiyuki, Jena Puru
Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284, USA.
J Chem Phys. 2010 May 21;132(19):194306. doi: 10.1063/1.3427293.
Using the density functional theory and generalized gradient approximation for exchange and correlation potential, we have performed an extensive search to obtain the ground state geometries of both neutral and anionic Au(16) cluster by considering over 200 low lying isomers. For the neutral Au(16) cluster we found a new T(d) compact structure to be the lowest energy configuration, which is nearly degenerate in total energy with the previously reported C(s) and C(2v) noncage structures. While the Au(16) (-) cluster, in agreement with previous calculations, is found to have a T(d) hollow cage structure, an isomer with a planar structure is found to be lower in energy. The photoelectron spectra from all the nine lowest energy isomers are calculated and compared with experiment to determine the possibility of their existence. Molecular dynamics simulations on both neutral and anionic Au(16) clusters are carried out to provide further insight into the origin and stability of these structures. Our comprehensive study allows us to answer the following questions: (1) Why are the adiabatic and vertical detachment energies of Au(16) cluster nearly identical when the lowest energy structures of the anion and the neutral are so very different? (2) How is Au(16) (-) formed? Is it born neutral and the extra electron attaches afterwards or is it born anionic and the structure evolves during the electron attachment process?
利用密度泛函理论以及交换关联势的广义梯度近似，我们通过考虑200多种低能异构体，对中性和阴离子Au(16)团簇的基态几何结构进行了广泛搜索。对于中性Au(16)团簇，我们发现一种新的T(d)紧凑结构是能量最低的构型，其总能量与先前报道的C(s)和C(2v)非笼状结构几乎简并。虽然与先前的计算结果一致，Au(16)(-)团簇具有T(d)空心笼状结构，但发现一种具有平面结构的异构体能量更低。计算了所有九个能量最低的异构体的光电子能谱，并与实验结果进行比较，以确定它们存在的可能性。对中性和阴离子Au(16)团簇都进行了分子动力学模拟，以进一步深入了解这些结构的起源和稳定性。我们的综合研究使我们能够回答以下问题：(1)当阴离子和中性的最低能量结构差异如此之大时，为什么Au(16)团簇的绝热和垂直脱附能几乎相同？(2)Au(16)(-)是如何形成的？它是先以中性形式生成，然后额外的电子附着其上，还是以阴离子形式生成，并且在电子附着过程中结构发生演化？
