Organisers

• Claudio Fusco (University of Duisburg-Essen, Theoretical Physics, D-47048 Duisburg)
• Andrea Vanossi (INFM-CNR National Research Center S3, and Physics Department, University of Modena and Reggio Emilia)

Supports

 CECAM

 COST - MolSimu

Description

While the laws of friction at the macroscopic level are well known, the fundamental understanding
of the frictional phenomena at the atomic scale is still unsatisfactory from many points of view.

Due to continuing device miniaturization, friction imposes serious constraints and limitations on the performance and lifetime of advanced technological microdevices; durable low-friction surfaces and suitable liquid and solid lubricants are increasingly in demand in hi-tech applications such as magnetic storage systems, microelectro-mechanical devices, and aerospace components. It has been estimated that about 6% of gross national product in developed countries is "wasted" on friction and related wear (nearly $800 billion per year in the USA alone).

Computer simulations are the most powerful theoretical tool to study atomic-scale frictional
processes, since they allow controlled numerical "experiments" where the geometry, sliding
conditions and interactions between the atoms can be varied at will, and where
the full dynamics of all atoms can be followed, unlike in real laboratory experiments.
Thanks to the computational resources available nowadays, it is possible to carry out
numerical simulations of systems approaching the size of those of interest for the
understanding of AFM experiments, albeit not yet on the appropriate time scales.
Different theoretical approaches can be used to simulate frictional processes at the
nanoscale, ranging from simple nonlinear models to complex molecular dynamics simulations
taking into account more realistic features.
It is thus necessary to bring together different communities and researchers working on
different aspects of atomic-scale friction and using different theoretical and
computational approaches. Moreover, in order to compare more effectively theoretical predictions with tribological experimental data and methodologies, this event envisages strategically the simultaneous presence of scientific renowned experimentalists working in the field.

Scientific Objectives

The goal of the workshop is to discuss how different approaches can be combined and to which extent new algorithms that bridge the atomistic time scales of the simulations and the experimental macroscopic time scales are effective. New results showing the progress in the understanding of the microscopic mechanisms of friction will be presented, and new predictions about the possibility to control and eventually reduce friction will be discussed.

References

[1] M. Urbakh, J. Klafter, D. Gourdon and J. Israelachvili The nonlinear nature of friction, Nature 430 525 (2004)

[2] O. M. Braun and A.G. Naumovets Nanotribology: Microscopic mechanisms of friction, Surface Science Reports 60 79 (2006)

[3] A. Socoliuc, E. Gnecco, S. Maier, O. Pfeiffer, A. Baratoff,R. Bennewitz and E. Meyer Atomic-Scale Control of Friction by ActuationofNanometer-Sized Contacts, Science 313 207 (2006)

[4] R. W. Carpick Controlling Friction, Science 313 184 (2006)

[5] M. H. Muser Towards an atomistic understanding of solid frictionby computer simulations, Computer Physics Communications 146 54 (2002)

[6] Y. S. Leng and S. Jiang Slow dynamics in atomic-force microscopy, Physical Review B 63 193406 (2001)

[7] S. Yu. Krylov, K. B. Jinesh, H. Valk, M. Dienwiebel and J. W. M. Frenken Thermally induced suppression of friction at the atomic scale, Physical Review E 71 065101(R) (2005)

[8] M. Evstigneev and P. Reimann Rate description of the stick-slipmotion in friction force microscopy experiments, Physical Review E 71 056119 (2005)

[9] Y. Braiman, J. Barhen and V. Protopopescu Control of Friction atthe Nanoscale, Physical Review Letters 90 094301 (2003)

[10] A. Socoliuc, R. Bennewitz, E. Gnecco and E. Meyer Transition from Stick-slip to Continuous Sliding in Atomic Friction:Entering a New Regime of Ultralow Friction, Physical Review Letters 92 134301 (2004)

[11] C. Fusco and A. Fasolino Power-law dependence of atomic friction, Applied Physics Letters 84 699 (2004)

[12] A. Vanossi, N. Manini, G. Divitini, G.E. Santoro and E. Tosatti Exactly quantized dynamics of classical incommensurate sliders, Physical Review Letters 97 056101 (2006)

[13] S. Dag and S. Ciraci Atomic scale study of superlow frictionbetween hydrogenated diamond surfaces, Physical Review B 70 241401(R) (2004)

[14] I. Y. Sokolov and G. S. Henderson Simulation of observability of atomic defects by atomic force microscopyin contact and non-contact modes, Surface Science 449 135 (2002)

[15] T. Trevethan and L. Kantorovich Molecular dynamics simulations of atomic scale processes at close approachin non-contact atomic force microscopy, Nanotechnology 16 S79 (2005)