Molecular dynamics simulation of thermal conductivity of silicon nanowires

Volz, Sébastian; Chen, Gang

doi:10.1063/1.124914

Cited by 419 publications

(329 citation statements)

References 19 publications

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“…1 κ is the thermal conductivity along the chain length, V is the system volume, Q z is the volume averaged heat flux along the chain axis direction (z-direction), and t is time. This approach has been used extensively to study the thermal conductivity of many different classes of materials and has shown good agreement with experiments and first principles based approaches 23,[40][41][42][43] . The quantity Q z (t)Q z (t + ′ t ) in Eq.…”

Section: Divergent Thermal Conductivity In Polymer Chainsmentioning

confidence: 90%

“…Although only 20% of the cases diverged, if one considers calculation of the ensemble average, the averaged thermal conductivity will diverge as a result. We calculated the thermal conductivity for 10,20,30,40, 80, 90, 120, and 150 unit cell chains, and the 30, 90 and 150 unit cell length chains exhibited divergent thermal conductivity. Similar to Henry and Chen's 23 results for PE, there were some simulations that exhibited clear convergence and others that exhibit clear divergence, with many cases falling in between these extremes.…”

Section: Resultsmentioning

confidence: 99%

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Understanding Divergent Thermal Conductivity in Single Polythiophene Chains Using Green–Kubo Modal Analysis and Sonification

Winters

DeAngelis

et al. 2017

J. Phys. Chem. A

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Abstract:We used molecular dynamics simulations, the Green-Kubo Modal Analysis (GKMA) method and sonification to study the modal contributions to thermal conductivity in individual polythiophene chains. The simulations suggest that it is possible to achieve divergent thermal conductivity and the GKMA method allowed for exact pinpointing of the modes responsible for the anomalous behavior. The analysis showed that transverse vibrations in the plane of the aromatic rings at low frequencies ~ 0.05 THz are primarily responsible. Further investigation showed that the divergence arises from persistent correlation between the three lowest frequency modes on chains. Sonification of the mode heat fluxes revealed regions where the heat flux amplitude yields a somewhat sinusoidal envelope with a long period similar to the relaxation time. This characteristic in the divergent mode heat fluxes gives rise to the overall thermal conductivity divergence, which strongly supports earlier hypotheses that attribute the divergence to correlated phonon-phonon scattering/interactions. Main text:In all substances, energy/heat is transferred through atomic motions. In electrically conductive materials, electrons can become the primary heat carriers, but in all phases of matter, atomic motions are always present and contribute to the thermal conductivity of every object. Here, we use the term "object" instead of "material" to emphasize that thermal conductivity is highly dependent on the actual structure of an object, that is, its internal atomic level structure and its larger nanoscale or microscale geometry [1][2][3][4][5][6] . In studying the physics of thermal conductivity, tremendous progress has been made over the last 20 years toward understanding various mechanisms that allow one to reduce thermal conductivity in solids 1,7 . This reduction is generally measured relative to a theoretical upper limiting maximum value that arises solely from the intrinsic anharmonicity within the interactions between atoms.In the limiting case, where the atomic interactions are perfectly harmonic, thermal conductivity tends to infinity because the normal modes of vibration do not interact, thus yielding effectively infinite phonon mean free paths and thermal conductivity. As a result, the notion of anharmonicity is critical, and perfectly harmonic interactions between atoms are physically unreasonable. This is because an asymmetry in the energetic well between atoms is an inherent consequence of finite bonding energy (e.g., at some point, the potential energy surface must become concave down). Although one can approach the harmonic limit at cryogenic temperatures, the notion that divergent thermal conductivity (e.g., anomalous thermal conductivity) might be realizable in a real material at room temperature seems theoretically impossible. However, in 1955 Fermi, Pasta, and Ulam (FPU) 8 made a "shocking little discovery" that even an anharmonic system can exhibit infinite thermal conductivity.FPU conducted a numerical experiment with a one-dimensio...

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Section: Divergent Thermal Conductivity In Polymer Chainsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Understanding Divergent Thermal Conductivity in Single Polythiophene Chains Using Green–Kubo Modal Analysis and Sonification

Winters

DeAngelis

et al. 2017

J. Phys. Chem. A

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“…On the other hand, the thermal conductivity of SWSNTs shown in Fig. 6 is much larger than that of Si nanowires (from 1 to 4 W/m·K) as reported in work by Chen and Volz [9]. This is attributed to the entirely different atomic structure of SWSNTs from Si nanowires.…”

Section: Thermal Conductivity and Specific Heat Of Swsntsmentioning

confidence: 50%

“…For numerical studies, molecular dynamics (MD) simulation has been widely employed to study the thermal transport in CNTs [2,8]. Previous study by Chen and Volz [9] explored the thermal conductivity of another 1D structure allotrope of Si nanowires using equilibrium MD (EMD) simulation. The result showed the thermal conductivity was about two orders of magnitude smaller than that of bulk Si.…”

Section: Introductionmentioning

confidence: 99%

Structure and thermophysical properties of single-wall Si nanotubes

Wang

Huang

Wang

et al. 2008

Physica B: Condensed Matter

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Structure and thermophysical properties of single-wall Si nanotubes, Physica B (2007), doi:10.1016/j.physb.2007.11.016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A c c e p t e d m a n u s c r i p t ABSTRACTIn this work, molecular dynamics (MD) simulation based on the environment-dependent interatomic potential is carried out to explore the structure, atomic energy distribution, and thermophysical properties of single-wall Si nanotubes (SWSNTs). The unique structure of SWSNTs leads to a wider range energy distribution than crystal Si (c-Si), and results in a bond order in the range of 4.8~5. The thermal conductivity of SWSNTs is much smaller than that of bulk Si, and shows significantly slower change with their characteristic size than that of Si films.Out of the three types of SWSNTs studied in this work, pentagonal SWSNTs have the highest thermal conductivity while hexagonal SWSNTs have the lowest one. The specific heat of SWSNTs is a little larger than that of bulk c-Si. Pentagonal and hexagonal SWSNTs have close specific heats which are a little larger than that of rectangular SWSNTs.

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“…Studies on silicon nanowires [7][8][9][10][11] have shown that diameter lowering induces thermal conductivity decrease. Theoretically, this observation is well described by an important number of phonon interactions with the medium boundaries.…”

Section: Nanowires Modelingmentioning

confidence: 99%