Coarse-grained molecular dynamics simulation of nanometer-thick polar lubricant films sheared between solid surfaces with random roughness

In hard disk drives (HDDs), the head-disk spacing needs to be reduced to less than 2 nm to achieve a target recording density of 4 Tbit/in² [1]. At such a small spacing, liquid perfluoropolyether (PFPE) lubricant films coated on disk surfaces are more frequently subjected to shear confined between the head and the disk. Therefore, a detailed understanding of the shear phenomenon is essential for improving the lubrication performance and the reliability of the HDDs. To directly and efficiently probe the molecular-scale structure and dynamics of nanometer-thick polar PFPE films sheared between solid surfaces with random roughness, we developed a coarse-grained (CG) model and carried out CG molecular dynamics simulations coupled with a dissipative particle dynamics thermostat [2].