Non-Monotonic Velocity Dependence of Atomic Friction

Non-monotonic dependence of the friction coefficient on heterogeneous stiffness

The complexity of the frictional dynamics at the microscopic scale makes difficult to identify all of its controlling parameters. Indeed, experiments on sheared elastic bodies have shown that the static friction coefficient depends on loading conditions, the real area of contact along the interfaces and the confining pressure. Here we show, by means of numerical simulations of a 2D Burridge-Kno...

Velocity dependence of friction of confined hydrocarbons.

We present molecular dynamics friction calculations for confined hydrocarbon "polymer" solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate and (b) polymer sliding on polymer. We discuss the velocity dependence of the frictional shear stress for both cases. In our simulations, the polymer films are very thin (approxim...

Velocity dependence of friction of confined polymers

Atomic simulations of kinetic friction and its velocity dependence at Al/Al and -Al2O3/ -Al2O3 interfaces

Kinetic friction during dry sliding along atomistic-scale Al 001 /Al 001 and -Al2O3 0001 / -Al2O3 0001 interfaces has been investigated using molecular dynamics MD with recently developed Reactive Force Fields ReaxFF . It is of interest to determine if kinetic friction variations predicted with MD follow the macroscopic-scale friction laws known as Coulomb’s law for dry sliding and Stokes’ fric...

Atomic force microscopy of chromatin arrays reveal non-monotonic salt dependence of array compaction in solution

Compaction of DNA in chromatin is a hallmark of the eukaryotic cell and unravelling its structure is required for an understanding of DNA involving processes. Despite strong experimental efforts, many questions concerning the DNA packing are open. In particular, it is heavily debated whether an ordered structure referred to as the "30 nm fibre" exist in vivo. Scanning probe microscopy has becom...