How reliable is the ReaxFF Potential for Describing the Structure of Alkanethiols on Gold? A Molecular Dynamics Study

2nd International Conference on Mathematical Modeling in Physical Sciences 2013

物理学;数学

Vasumathi, V.^1 ; Cordeiro, Maria Natalia D. S.^1

REQUIMTE, Department of Chemistry and Biocemistry, University of Porto, Rua do Campo Alegre 687, Porto 4168-007, Portugal^1

关键词: Alkanethiols;    Alkyl thiols;    Embedded-atom method;    First principles;    MD simulation;    Methanethiol;    Novel structures;    Reactive potentials;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/490/1/012006/pdf
DOI  :  10.1088/1742-6596/490/1/012006

来源: IOP

【 摘 要 】

The structures of self-assembled monolayers (SAMs) of short (methyl) and long (hexyl) chain alkyl thiols on the clean gold (111) surface were modelled using for the Au-S interactions either the reactive ReaxFF potential or the well known non-reactive Morse potential, while for the Au-Au interactions either the ReaxFF potential or an embedded-atom method (EAM). Analysis of the MD trajectories of possible SAM structures suggests that disordering of interfacial Au atoms is definitely driven by the gold-sulphur interactions. Our MD results reveal a novel structure where two methanethiol molecules are bound to a gold adatom that has been lifted from the surface at 300 K, and the same kind of RS-Au-SR motif was also observed for hexanethiol at 600 K but not at 300 K. What is more, the above motif is only observed for the reactive ReaxFF potential. Moreover, these results are in clear agreement with recent experiments and more costly first principles-based MD simulations. These findings strongly support the use of reactive potentials such as ReaxFF for gathering an accurate description of Au-S interactions in inexpensive classical MD simulations.