Jiang De-en, Tiago Murilo L, Luo Weidong, Dai Sheng
Chemical Sciences Division and Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
J Am Chem Soc. 2008 Mar 5;130(9):2777-9. doi: 10.1021/ja710991n. Epub 2008 Feb 8.
Recently obtained single-crystal structure of a thiolate-protected gold cluster shows that all thiolate groups form "staple" motifs on the cluster surface. To find out the driving force for such a formation, we use first-principles density functional theory simulations to model formation of "staple" motifs on an Au38 cluster from zero to full coverage. By geometry optimization, molecular dynamics, and simulated annealing, we show that formation of "staples" is strongly preferred on a cluster surface and helps stabilize the cluster by pinning the surface Au atoms and increasing the HOMO-LUMO gap. We devise a method to generate initial structural models for thiolate-protected gold clusters by adding "staples" to the cluster surface. Using this method, we obtain a staple-covered, low-energy structure for Au38(SCH3)24, a much studied cluster whose structure is not yet known. Optical band-edge energy computed from time-dependent DFT for our Au38(SCH3)24 structure shows good agreement with experiment.
最近获得的一种硫醇盐保护的金簇单晶结构表明，所有硫醇盐基团在簇表面形成“订书钉”图案。为了找出这种形成的驱动力，我们使用第一性原理密度泛函理论模拟来模拟在Au38簇上从零覆盖到完全覆盖的“订书钉”图案的形成。通过几何优化、分子动力学和模拟退火，我们表明“订书钉”在簇表面的形成是非常有利的，并且通过固定表面金原子和增加HOMO-LUMO能隙来帮助稳定簇。我们设计了一种通过在簇表面添加“订书钉”来生成硫醇盐保护的金簇初始结构模型的方法。使用这种方法，我们获得了Au38(SCH3)24的一种被大量研究但结构尚不清楚的簇的订书钉覆盖的低能量结构。从我们的Au38(SCH3)24结构的含时密度泛函理论计算得到的光学带边能量与实验结果吻合良好。
