Friction coefficient for hexagonal boron nitride surfaces from ab initio calculations

The friction coefficient for two hexagonal boron nitride (h-BN) sheets was estimated on the basis of ab initio calculations. Several models, both cluster and periodic one, were applied to describe h-BN and the interactions between its dimers. In all cases, the gauche orientation is favoured, the interaction energies being virtually independent of the size of the model. The friction coefficient values, in contrast, converge towards the values from periodic calculations. At the lower limit of the periodic system, the friction coefficients vary between 0.226 and 0.265 depending on the orientations of the dimers. The calculations are in good agreement with an experimental study of the friction [Saito and Honda, Wear 237 (2000) 253], which suggested a friction coefficient of 0.23-0.25 for h-BN.