Sliding system geometry

We wish to study the effects of planar Couette flow on a system that is in the NPT (fully flexible box) ensemble. In this section, we consider the effects of the external field alone on the dynamics of the cell. The intrinsic cell dynamics arising out of the internal stress is assumed implicitly. The constant NPT ensemble can be employed in simulations of crystalline materials, so as to perform dynamics consistent with the cell geometry. In this section, we assume that the shear field is applied to anisotropic systems such as liquid crystals, or crystalline polytetrafluoroethylene. For an anisotropic solid, we assume that the shear field is oriented in such a way that different weakly interacting planes of atoms in the solid slide past each other. The methodology presented is quite general hence it is straightforward to apply for simulations of shear flow in liquids in a cubic box, as well. 

The principle of most multiple-anvil systems is to compress a sample volume, in the shape of a regular polyhedron, by a variable number of identically shaped pistons which advance towards each other. Thus, tetrahedral, cubic, and octahedral compression have successfully been achieved. In this type of compression, the thrust is strictly along the axis of the pistons. Other geometries which introduce nonaxial (shear) components, such as hexahedral geometries, have proven to be remarkably unsuccessful and have been abandoned. Sliding-... 

As the FlexControl MTP Slide Adapter 11 geometry file uses a fractional distance coordinate system where the distance between each point in the regular array is separated by exactly 0.086957 units, a new geometry file can be created in this coordinate system to acquire data at the bead positions. 

Elastohydrodynamic (EHD) lubrication occiors between loaded, rolling or sliding, lubricated contacts where the geometry and hardness of the two surfaces produce very high pressures in the contact. In such systems, two effects of this pressure, to elastically flatten the surfaces and to greatly enhance the viscosity of the lubricant, combine to generate hydrodynamic oil films of typically 50-5000 nm thickness. 

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