title: A computational chemistry study on friction of h-MoS₂. Part II. Friction anisotropy.
abstract: In 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. The superimposed structures with misfit angle of 0° and 60° are commensurate, and others are incommensurate. Friction dynamics was simulated by applying an external pressure and a sliding speed to the model. During friction simulation, the incommensurate structures showed extremely low friction due to cancellation of the atomic force in the sliding direction, leading to smooth motion. On the other hand, in commensurate situations, all the atoms in the sliding part were overcoming the atoms in counterpart at the same time while the atomic forces were acted in the same direction, leading to 100 times larger friction than incommensurate situation. Thus, lubrication by MoS(2) strongly depended on its interlayer contacts in the atomic scale. According to part I of this paper [Onodera, T., et al. J. Phys. Chem. B 2009, 113, 16526-16536], interlayer sliding was source of friction reduction by MoS(2) and was originally derived by its material property (interlayer Coulombic interaction). In addition to this interlayer sliding, the rotational disorder was also important to achieve low friction state.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-10-205 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Tasuku
authors.initials: T
authors.lastname: Onodera
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Morita
authors.forename: Ryo
authors.initials: R
authors.lastname: Nagumo
authors.forename: Ryuji
authors.initials: R
authors.lastname: Miura
authors.forename: Ai
authors.initials: A
authors.lastname: Suzuki
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Tsuboi
authors.forename: Nozomu
authors.initials: N
authors.lastname: Hatakeyama
authors.forename: Akira
authors.initials: A
authors.lastname: Endou
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Takaba
authors.forename: Fabrice
authors.initials: F
authors.lastname: Dassenoy
authors.forename: Clotilde
authors.initials: C
authors.lastname: Minfray
authors.forename: Lucile
authors.initials: L
authors.lastname: Joly-Pottuz
authors.forename: Momoji
authors.initials: M
authors.lastname: Kubo
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Martin
authors.forename: Akira
authors.initials: A
authors.lastname: Miyamoto
mesh_terms: D016880:Anisotropy; D004220:Disulfides / Q000737:chemistry*; D017276:Friction; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D008982:Molybdenum / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D004220:Disulfides; D008982:Molybdenum; C082964:molybdenum disulfide