Related papers: Atomic scale friction of molecular adsorbates duri…
The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent…
The pioneer work of Krim and Widom unveiled the origin of the viscous nature of friction at the atomic scale. This generated extensive experimental and theoretical activity. However, fundamental questions remain open like the relation…
We report on the frictional properties of thin ($\approx \mu m$) poly(dimethylacrylamide) hydrogel films within contacts with spherical silica probes. In order to focus on the contribution to friction of interfacial dissipation, a dedicated…
Simulations of the kinetic friction due to a layer of adsorbed molecules between two crystalline surfaces are presented. The adsorbed layer naturally produces friction that is consistent with Amontons' laws and insensitive to parameters…
We investigate atomic scale friction between clean graphite surfaces by using molecular dynamics. The simulation reproduces atomic scale stick-slip motion and low frictional coefficient, both of which are observed in experiments using…
We present the results of large scale molecular dynamics simulations aimed at understanding the origins of high friction coefficients in pure metals, and their concomitant reduction in alloys and composites. We utilize a series of targeted…
Friction experiments were conducted on hydrogel thin films sliding against a rigid sphere in a low velocity regime where molecular adsorption at the sliding interface sets the friction force, through a dissipative…
To analyze hydration effects on macromolecular diffusion, the friction coefficients of macromolecules were examined using molecular dynamics simulations with an all-atom model. In the present study, a method was introduced to decompose the…
Molecular dynamics simulations are used to study contact between a rigid, nonadhesive, spherical tip with radius of order 30nm and a flat elastic substrate covered with a fluid monolayer of adsorbed chain molecules. Previous studies of bare…
Experiments performed by friction force microscopy at atomic-scale surface steps on graphite, MoS$_2$, and NaCl in ambient conditions are presented. Both step-down and step-up scans exhibit higher frictional forces at the edge, but…
Molecular adsorbates on metal surfaces exchange energy with substrate phonons and low-lying electron-hole pair excitations. In the limit of weak coupling, electron-hole pair excitations can be seen as exerting frictional forces on…
In this manuscript, we provide a general theory for how surface phonons couple to molecular adsorbates. Our theory maps the extended dynamics of a surface's atomic vibrational motions to a generalized Langevin equation, and by doing so…
We analyze theoretically the effect of friction on quartz crystal microbalance (QCM) measurements that probe soft (viscoelastic) films and biomolecular layers adsorbed from aqueous solutions. While water provides a natural environment for…
Molecular dynamics study of a thin (one to five layers) lubricant film between two substrates in moving contact are performed using Langevin equations with an external damping coefficient depending on distance and velocity of atoms relative…
In studies of dynamical systems, helium atoms scatter coherently from an ensemble of adsorbates as they diffuse on the surface. The results give information on the co-operative behaviour of interacting adsorbates and thus include the…
We study the non-contact friction between an atomic force microscope tip and a metal substrate in the presence of bias voltage. The friction is due to energy losses in the sample created by the electromagnetic field from the oscillating…
Traditional laws of friction believe that the friction coefficient of two specific solids takes constant value. However, molecular simulations revealed that the friction coefficient of nanosized asperity depends strongly on contact size and…
We investigate the influence of spatial dispersion on atom-surface quantum friction. We show that for atom-surface separations shorter than the carrier's mean free path within the material, the frictional force can be several orders of…
Nanocrystalline metals, i.e. metals in which the grain size is in the nanometer range, have a range of technologically interesting properties including increased hardness and yield strength. We present atomic-scale simulations of the…
Contacts between particles in dense, sheared suspensions are believed to underpin much of their rheology. Roughness and adhesion are known to constrain the relative motion of particles, and thus globally affect the shear response, but an…