Triggering waves in nonlinear lattices: Quest for anharmonic phonons and corresponding mean-free paths

Li, Sha; Liu, Junjie; Hänggi, Peter; Wu, Chao; Li, Baowen

doi:10.1103/physrevb.90.174304

Cited by 35 publications

(49 citation statements)

References 56 publications

(116 reference statements)

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“…Because the MFPs reported in Ref. [21] correspond to the decay length of vibrational amplitude and not the square of amplitude as in our definition, we divide the mean free paths of Ref. [21] by two to allow for a meaningful comparison.…”

Section: B Mean Free Pathsmentioning

confidence: 99%

“…[21] correspond to the decay length of vibrational amplitude and not the square of amplitude as in our definition, we divide the mean free paths of Ref. [21] by two to allow for a meaningful comparison. This procedure ensures that for a harmonic chain coupled to dissipative Langevin heat baths with coupling constant γ (see Sec.…”

Section: B Mean Free Pathsmentioning

confidence: 99%

“…(6) to the equilibrium MFPs [21] determined from the decay of velocity cross correlations at each frequency ω. Because the MFPs reported in Ref.…”

Section: B Mean Free Pathsmentioning

confidence: 99%

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Nonequilibrium phonon mean free paths in anharmonic chains

et al. 2015

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Harnessing the power of low-dimensional materials in thermal applications calls for a solid understanding of the anomalous thermal properties of such systems. We analyze thermal conduction in one-dimensional systems by determining the frequency-dependent phonon mean free paths (MFPs) for an anharmonic chain, delivering insight into the diverging thermal conductivity observed in computer simulations. In our approach, the MFPs are extracted from the length dependence of the spectral heat current obtained from nonequilibrium molecular dynamics simulations. At low frequencies, the results reveal a power-law dependence of the MFPs on frequency, in agreement with the diverging conductivity and the recently determined equilibrium MFPs. At higher frequencies, however, the nonequilibrium MFPs consistently exceed the equilibrium MFPs, highlighting the differences between the two quantities. Exerting pressure on the chain is shown to suppress the mean free paths and to generate a weaker divergence of MFPs at low frequencies. The results deliver important insight into the anomalous thermal conduction in low-dimensional systems and also reveal differences between the MFPs obtained from equilibrium and nonequilibrium simulations.

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Section: B Mean Free Pathsmentioning

confidence: 99%

Section: B Mean Free Pathsmentioning

confidence: 99%

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Nonequilibrium phonon mean free paths in anharmonic chains

et al. 2015

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“…The nontrivial scenario where this assumption holds is the two-segment model studied herein where due to the weak interfacial coupling each segment can be assumed to attain a local equilibrium with the temperature of its respective bath. Furthermore, we ensure that each segment comprises only of a few atoms such that the mean-free path of the phonons, which is typically hundreds of atoms [30,31], is much longer than the segment length. Hence, QSCPT could be applied independently to the two segments without the need to deal with nonequilibrium averages [32].…”

Section: Model and Theorymentioning

confidence: 99%

Interfacial thermal transport with strong system-bath coupling: A phonon delocalization effect

Thingna

Cao

2018

Phys. Rev. B

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We study the effect of system-bath coupling strength on quantum thermal transport through the interface of two weakly coupled anharmonic molecular chains by using a quantum self-consistent phonon approach. The approach inherently assumes that the two segments (anharmonic molecular chains) are approximately in local thermal equilibrium with respect to the baths that they are connected to and transforms the strongly anharmonic system into an effective harmonic one with a temperature-dependent transmission. Despite the approximations, the approach is ideal for our setup, wherein the weak interfacial coupling guarantees an approximate local thermal equilibrium of each segment and short chain length (less than the phonon mean-free path) ensues from the effective harmonic approximation. Remarkably, the heat current shows a resonant to bi-resonant transition due to the variations in the interfacial coupling and temperature, which is attributed to the delocalization of phonon modes. Delocalization occurs only in the strong system-bath coupling regime and we utilize it to model a thermal rectifier whose ratio can be nonmonotonically tuned not only with the intrinsic system parameters but also with the external temperature.

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“…Since then, effective phonons [61][62][63][64] are regarded as the energy carriers in nonlinear lattices.…”

Section: Introductionmentioning

confidence: 99%