INFIQC/CONICET, Departamento de Matemática y Física, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba (XUA5000), Córdoba, Argentina.
Phys Chem Chem Phys. 2011 Apr 14;13(14):6500-6. doi: 10.1039/c0cp02921a. Epub 2011 Mar 9.
A new semiempirical potential, based on density functional calculations and a bond-order Morse-like potential, is developed to simulate the adsorption behavior of thiolate molecules on non-planar gold surfaces, including relaxing effects, in a more realistic way. The potential functions include as variables the metal-molecule separation, vibrational frequencies, bending and torsion angles between several pairs of atom types and the coordination number of both the metal (Au) and thiolate groups. The potential was parameterized based on a set of density functional calculations of molecular adsorption in several surface sites (i.e. hollow, bridge, top, on-top Au adatom and the novel staple motif) for different crystalline facets, i.e. Au(111) and (100). Langevin dynamics simulations have been performed to study the capping effects of alkanethiolates molecules on Au nanoparticles in the range 1-4 nm. The simulation results reveal an enhancement of the coverage degree whilst the nanoparticles diameter decreases. A high surface disorder due to the strong S-Au bond was found, in very good agreement with very recent experimental findings [M. M. Mariscal, J. A. Olmos-Asar, C. Gutierrez-Wing, A. Mayoral and M. J. Yacaman, Phys. Chem. Chem. Phys., 2010, 12, 11785].
一种新的半经验势，基于密度泛函计算和键序 Morse 型势，被开发出来以更真实的方式模拟硫醇分子在非平面金表面上的吸附行为，包括弛豫效应。势函数包括金属-分子分离、振动频率、几个原子对类型之间的弯曲和扭转角度以及金属（Au）和硫醇基团的配位数。该势基于一系列在不同晶面（即 Au(111)和(100)）的几个表面位点（即空穴、桥、顶、Au 顶原子和新颖的订书钉基序）上分子吸附的密度泛函计算进行参数化。朗之万动力学模拟已被用于研究不同直径的 Au 纳米粒子上烷硫醇分子的封端效应。模拟结果表明，随着纳米粒子直径的减小，覆盖率程度增强。由于 S-Au 键很强，表面无序度很高，这与最近的实验结果非常吻合[M. M. Mariscal、J. A. Olmos-Asar、C. Gutierrez-Wing、A. Mayoral 和 M. J. Yacaman，Phys. Chem. Chem. Phys.，2010，12，11785]。
