2021 Fiscal Year Annual Research Report
Control the transport of phonon in a broad frequency range in low dimensional materials
| Project/Area Number |
21J21382
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| Allocation Type | Single-year Grants |
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| Research Institution | The University of Tokyo |
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Principal Investigator |
DING WENYANG 東京大学, 工学系研究科, 特別研究員(DC1)
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| Project Period (FY) |
2021-04-28 – 2024-03-31
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| Keywords | vdW heterostructures / Materials informatics / Bayesian optimization |
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| Outline of Annual Research Achievements |
Bayesian optimization is performed to explore the controllability of thermal transport in vdW graphene-WS2 heterostructures and identify the ultimate heterostructure that gives minimum thermal conductivity from 16384 possible candidates. The global optimum heterostructure with the minimum thermal conductivity is obtained by repeating 15 rounds (calculating 150 candidates) in first optimization procedure and 34 rounds (calculating 340 candidates) in second optimization procedure. The thermal conductivity of the optimized heterostructure is only 0.048 W/m-K, which is only about 5.4% (13%) of the pristine graphene (WS2).
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
My original plan for the first year is calculation of thermal conductivity for two dimensional material and calculation of phonon properties for the two dimensional material to understand the underlying physical mechanism. Now I not only constructed heterostructures by stacking different two dimensional material and calculate their thermal conductivities, but also performed Bayesian optimization to get the optimized heterostructure with desired property. Moreover, the phonon transmission of the optimized structure is also calculated, and the result shows that the phonon transmission of the optimized structure is suppressed throughout the full frequency range.
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| Strategy for Future Research Activity |
1. Since Bayesian optimization pursues biased sampling, it may suffer from possibility of being trapped in the local optimum. Therefore, we will implement replica-exchange monte carlo method, which searches a broader parameter space by fair sampling and is more likely to find the global minimum of Van der Waals (vdW) graphene-WS2 heterostructures at the expense of efficiency.
2. Atomistic Green's Function, which can generate individual phonon behavior information, has never been imposed on heterostructure. In our future study, the Atomistic Green's function will be performed to understand the underlying physical mechanism for the significantly suppressed thermal conductivity of the optimized heterostructure.
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