Abstract
Alkanethiol molecules chemically adsorbed on the gold (Au) surface are considered to investigate the characteristics of the Self-assembled monolayer (SAM) interface at room temperature. The analysis is based on the molecular dynamics (MD) method. We use two alkanethiols with different chain lengths, that is, ethanethiol (C_2H_5SH) and 1-propanethiol (C_3H_7SH) as the adsorbed molecule on the Au (111) surface. The probability distribution of the tilt angle of SAM molecules is obtained. It is shown that the peak position of tilt angle in the distribution has 30.0° for ethanethiol, and 28.3° for propanethiol, respectively. The calculated tilt angle agrees well with the previous MD result. The detailed structure of the adsorption position of thiol molecule also obtained. It is found that many thiol molecules for ethanethiol are seated on a fcc-hollow site of the surface although the thiol molecules for ethanethiol mainly have the adsorption position of a hcp-hollow site of the surface.
