Effects and correction of angular momentum non-conservation in RNEMD for calculating thermal conductivity

Yang, Hong-Ao; Cao, Bing‐Yang

doi:10.1016/j.commatsci.2020.109753

Cited by 6 publications

(2 citation statements)

References 31 publications

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“…Originally, it was implemented for transport studies of Lennard-Jones fluids, but later on, it has been applied to more complex systems, such as, carbon and graphene nanosystems [23][24][25][26][27][28]. The RNEMD method has been found to be quite robust for studying thermal transport properties, but also has some issues that have been pointed out in recent works, and improvements have been suggested in some cases [29][30][31][32].…”

Section: Rnemd Simulationsmentioning

confidence: 99%

Heat transport in long-ranged anharmonic oscillator models

Bagchi

2021

Preprint

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In this work, we perform a detailed study of heat transport in one dimensional long-ranged anharmonic oscillator systems, such as the long-ranged Fermi-Pasta-Ulam-Tsingou model. For these systems, the long-ranged anharmonic potential decays with distance as a power-law, controlled by an exponent δ ≥ 0. For such a nonintegrable model, one of the recent results that has captured quite some attention is the puzzling ballistic-like transport observed for δ = 2, reminiscent of integrable systems. Here, we first employ the reverse nonequilibrium molecular dynamics simulations to look closely at the δ = 2 transport in three long-ranged models, and point out a few problematic issues with this simulation method. Next, we examine the process of energy relaxation, and find that relaxation can be appreciably slow for δ = 2 in some situations. We invoke the concept of nonlinear localized modes of excitation, also known as discrete breathers, and demonstrate that the slow relaxation and the ballistic-like transport properties can be consistently explained in terms of a novel depinning of the discrete breathers that makes them highly mobile at δ = 2. Finally, in the presence of quartic pinning potentials we find that the long-ranged model exhibits Fourier (diffusive) transport at δ = 2, as one would expect from short-ranged interacting systems with broken momentum conservation. Such a diffusive regime is not observed for harmonic pinning.

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Section: Rnemd Simulationsmentioning

confidence: 99%

Heat transport in long-ranged anharmonic oscillator models

Bagchi

2021

Preprint

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“…For instance, low values lead to high temperature gradients, and the steady-state regime is reached faster than at high values [ 12 ], but, on the other hand, at low values, a modeled substance can be in the periodic box at different phases, for example, in liquid and solid states. In addition, high values of the period of the velocity exchange can lead to big errors [ 13 ], whereas low values cause velocity drifting [ 14 ], and the thermal conductivity can be affected by the wave motion heat conduction [ 15 ]. For the elimination of such cases, one needs to find the optimal period of the velocity exchange.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Thermal Conductivities of Rubbers by MD Simulations—New Insights

2022

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In this article, two main approaches to the prediction of thermal conductivities by molecular dynamics (MD) simulations are discussed, namely non-equilibrium molecular dynamics simulations (NEMD) and the application of the Green–Kubo formula, i.e., EMD. NEMD methods are more affected by size effects than EMD methods. The thermal conductivities of silicone rubbers in special were found as a function of the degree of crosslinking. Moreover, the thermal conductivities of thermoplastic polyurethane as function of the mass fraction of soft segments were obtained by those MD simulations. All results are in good agreement with data from the experimental literature. After the analysis of normalized heat flux autocorrelation functions, it has been revealed that heat in the polymers is mainly transferred by low-frequency phonons. Simulation details as well as advantages and disadvantages of the single methods are discussed in the article.

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Enhanced heat transfer and thermal storage performance of molten K2CO3 by ZnO nanoparticles: A molecular dynamics study

Ji,

Yang,

et al. 2024

Journal of Molecular Liquids

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Effects and correction of angular momentum non-conservation in RNEMD for calculating thermal conductivity

Cited by 6 publications

References 31 publications

Heat transport in long-ranged anharmonic oscillator models

Heat transport in long-ranged anharmonic oscillator models

Prediction of Thermal Conductivities of Rubbers by MD Simulations—New Insights

Enhanced heat transfer and thermal storage performance of molten K2CO3 by ZnO nanoparticles: A molecular dynamics study

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