Computational material discovery is under intense study owing to its ability to explore the vast space of chemical systems. Neural network potentials (NNPs) have been shown to be particularly effective in conducting atomistic simulations for such purposes. However, existing NNPs are generally designed for narrow target materials, making them unsuitable for broader applications in material discovery.
View Article and Find Full Text PDFAn impressive superlow coefficient of friction (CoF) as low as 0.004 (nearly equivalent to the rolling coefficient) was obtained by sliding a steel ball against a tetrahedral amorphous diamond-like carbon (ta-C) coating in glycerol under a boundary lubrication regime. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) revealed substantial changes in the surface chemistry and topography in the friction track.
View Article and Find Full Text PDFMolecular Dynamics has been used to simulate the anti-wear chemistry of zinc dialkyl dithiophosphate (ZDDP). The model simulates the digestion of abrasive particles into the zinc polyphosphate glass. The main result is that the driving force for the tribochemical reaction is not temperature but entropy due to mechanical mixing at the atomic scale.
View Article and Find Full Text PDFIn this work, the friction anisotropy of hexagonal MoS(2) (a well-known lamellar compound) was theoretically investigated. A molecular dynamics method was adopted to study the dynamical friction of two-layered MoS(2) sheets at atomistic level. Rotational disorder was depicted by rotating one layer and was changed from 0° to 60°, in 5° intervals.
View Article and Find Full Text PDFUsing a hybrid quantum chemical/classical molecular dynamics method, we have studied the tribochemical reaction dynamics of molybdenum dithiocarbamate (MoDTC), a commonly used friction modifier in automobile engine oils. MoDTC molecule adsorbed on rubbing nascent iron surface was situated. We firstly investigated the dynamic behavior of MoDTC molecule on the rubbing Fe(001) surface.
View Article and Find Full Text PDFIn this work, we theoretically investigated the friction mechanism of hexagonal MoS(2) (a well-known lamellar compound) using a computational chemistry method. First, we determined several parameters for molecular dynamics simulations via accurate quantum chemistry calculations and MoS(2) and MoS(2-x)O(x) structures were successfully reproduced. We also show that the simulated Raman spectrum and peak shift on X-ray diffraction patterns were in good agreement with those of experiment.
View Article and Find Full Text PDFTo study the atomistic behavior of the phosphoric ester molecule on the nascent Fe surface under boundary lubrication conditions, we adopted a hybrid tight-binding quantum chemical molecular dynamics method. First, we investigated chemical interactions between phosphoric ester and the nascent Fe surface. Phosphoric ester was shown to interact with the nascent Fe surface, forming both covalent and ionic bonds.
View Article and Find Full Text PDF