Chain Length Effect on Surface Stress of Alkanethiolates Adsorbed onto AU(111) Surface: a van der Waals Density Functional Study

Abstract

First-principles calculations were employed to investigate the adsorption-induced surface stress of self-assembled alkanethiolate monolayers on a Au(111) surface as a function of the alkyl chain length. A recently developed fully nonlocal van der Waals density functional was used to accurately account for the chain-chain interactions. We found that surface charge redistribution produces compressive surface stress, while chain-chain interactions produce tensile surface stress. The stress induced by surface charge redistribution is about one order of magnitude greater than that of chain-chain interactions. We observed that the chain-chain interactions play an important role in determining the molecular configuration during adsorptions, and also contribute significantly to the induced anisotropic tensile (positive) surface stress. As the chain length increases the tensile stress increases at a rate of ∼ 0.32 (∼ 0.18) N/m for the direction perpendicular (parallel) to the chain tilt direction.

Size, Temperature, and Strain‐Rate Dependence on Tensile Mechanical Behaviors of Ni3Sn4 Intermetallic Compound Using Molecular Dynamics Simulation

“…It should be noted that the Ni 3 Sn 4 nanowires consist of a circular cross section mainly because they would possess the most stable and natural crosssectional configuration [42][43][44]. Under the same length of 100Å, three different nanowire diameters, namely, 14Å 14, 18Å (18 ), and 22Å (22 ), are considered in the tensile MD simulation, in which they are labeled with "14 × 100, " "18 × 100, " and "22 × 100, " respectively. Figure 4 shows the atomic models for these Ni 3 Sn 4 nanowires.…”

“…Atomic modeling can limit the shortage of experimental approaches and also supplement laboratory assessment. Over the past years, various computational approaches have been proposed, including equivalent-continuum modeling (ECM) [20][21][22][23][24], molecular dynamics (MD) simulation [4,[25][26][27][28][29][30][31], and quantum mechanics (QM) simulation [19,[32][33][34]. For example, Cheng et al [35] and Lee et al [36] evaluated the elastic properties of Ni 3 Sn 4 monocrystal by performing density functional theory (DFT) calculations within the generalized-gradient approximation (GGA) and local density approximation (LDA) using the software CASTEP [37,38].…”

Density Functional Theory Investigations of Ferrocene-Terminated Self-Assembled Monolayers: Electronic State Changes Induced by Electric Dipole Field of Coadsorbed Species

“…63 Although it has been known that the Au(111) surface is reconstructed during the SAM formation, 39,42,64,65 we did not intentionally create gold vacancies and adatoms before structural optimizations, as in the cases of previous studies. 21,[34][35][36][37][38]40,41,[43][44][45]66 In addition, as for the initial structure, sulfur atoms of thiol derivatives were positioned at the bridge sites slightly shifted to the face-centered cubic (fcc)-hollow site. [34][35][36][37]42,43,45 Then, the adsorbates and the top two layers of gold atoms were allowed to relax.…”

Direct Determination of a Small-Molecule Drug, Valproic Acid, by an Electrically-Detected Microcantilever Biosensor for Personalized Diagnostics

“…First, the response signal of a cantilever was generated by the adsorption of 100 mM SAM biolinker, resulting in changes to resistance and surface stress of 0.12 Ω and 0.8 N·m − 1 in compressive stress. During the adsorption of the alkanethiolate self-assembled monolayer (SAM) on the cantilever’s Au surface, the overall surface stresses originate from two types of interactions: surface charge redistribution and chain-chain interaction [ 19 , 20 ]. Meanwhile, surface charge redistribution gives rise to compressive surface stress, while chain-chain interactions produce tensile surface stress.…”

“…Meanwhile, surface charge redistribution gives rise to compressive surface stress, while chain-chain interactions produce tensile surface stress. Meanwhile, the stress induced by surface charge redistribution is about one order of magnitude greater than that of the chain-chain interactions [ 20 ]. As a result, the alkanethiolate SAM adsorption on the cantilever sensor’s gold surface generates a deflection of compressive surface stress.…”