Browsing by Author "Leitner, D. M."
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Item Open Access Model for phononic energy dissipation in friction(American Physical Society, 1999) Buldum, A.; Leitner, D. M.; Çıracı, SalimWe have developed a microscopic model of phononic energy dissipation in friction that involves the generation of a local excess phonon distribution in a nanoparticle between two sliding objects, and its damping into the objects. The conversion of the energy stored in the nanoparticle into excess phonons and their decay rates are calculated. The model can be extended to include randomly distributed nanoparticles and phonon-phonon interaction through anharmonic couplings. By using this model we present a quantitative analysis of energy dissipation in sliding friction.Item Open Access Reduced density matrix approach to phononic dissipation in friction(2000) Özpineci, A.; Leitner, D. M.; Çıracı, SalimUnderstanding mechanisms for energy dissipation from nanoparticles in contact with large samples is a central problem in describing friction microscopically. Calculation of the reduced density matrix appears to be the most suitable method to study such systems that are coupled to a large environment. In this paper, the time evolution of the reduced density matrix has been evaluated for an arbitrary system coupled to a heat reservoir. The formalism is then applied to study the vibrational relaxation following the stick-slip motion of an asperity on a surface. The frequency and temperature dependence of the relaxation time is also determined. Predictions of the reduced density matrix are compared with those obtained by using the Golden Rule approach.Item Open Access Thermal conduction through a molecule(E D P Sciences, 1999) Buldum, A.; Leitner, D. M.; Çıracı, SalimThe quantum features of phononic thermal conduction through a molecule between two reservoirs have been studied in the weak-coupling limit. As opposed to ballistic heat transfer through a uniform bridge or atomic chain strongly coupled to reservoirs investigated earlier, thermal conductance in the present case shows a nonlinear temperature dependence that is sensitive to the mode frequencies of the molecule.