Quantum paradigms in hydrogen storage in nanostructures
| Project/Area Number |
19K15397
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 28030:Nanomaterials-related
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2024-03-31
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| Project Status |
Granted (Fiscal Year 2022)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2022: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2021: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2020: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
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| Keywords | nanostructure / nanojunction / ortho-para / hydrogen / DFT / NEGF / anisotropic / molecule / graphene / quantum effects / hydrogen storage / nuclear spin / 2D nanostructure / transition metal / Quantum effects / nanostructures / ortho-para conversion / molecular rotations |
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| Outline of Research at the Start |
The current trend in high-capacity hydrogen storage research is the usage of nanomaterials due to their large surface areas and amenability to engineering. Due to its light mass, quantum effects are likely to play essential roles in hydrogen binding and dynamics in nanostructures. In this research, the quantum mechanical effects in hydrogen storage will be explored by means of first principles calculations and time-dependent perturbation theory. The results of this research are expected to introduce new paradigms in research approaches to hydrogen storage and hydrogen related technologies.
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| Outline of Annual Research Achievements |
This year, the rotational effects of H2 molecule in a nanojunction was investigated by means of model Hamiltonian calculations. The adsorption and interaction parameters were obtained from first principles calculations based on the density functional theory. The orientation-dependent current was calculated using NEGF formalism. Ihe vibrational effects is also incorporated through the electron-phonon coupling. Our results recovered the previously understood electron-phonon effects in the quantum dot system where step-like features in the current and periodic peaks in the conductance are attributed to the Frank-Condon excitations. We also derived an expression for the interaction between the metal junctions and H2 at a microscopic level accounting for the orientation of the molecule with respect to the junctions. We found that the current is suppressed when the molecular orientation is parallel to the surfaces of the metals. Further, the spectral function (SF) at this orientation narrows indicating the reduction of the electron hopping between the junction and H2.
This strong orientation effects can be similarly seen in the rotational averaged SF and current. The J=0,m=0 (para) SF is narrow compared to J=1,m=0 (ortho). The J=1,m=1 SF is narrowest among the rotational states investigated. In the gas phase, J=1,m=0 and J=1,m=1 states are degenerate in energy and both SF of these states are expected to be the similar. The electronic interaction between the metal junctions and H2 cause the splitting of these states and results in anisotropic current in the nanojunction.
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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
The model calculations for ortho-para conversion as well as the NEGF calculations for anisotropic current in a nanojunction have been developed and the computation could proceed smoothly. The parameters from both these calculations were obtained directly from DFT calculations without much difficulty. The construction of potential energy surfaces (PES) using neural network potential (NNP) remains challenging due to the parameters involved in the training.
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| Strategy for Future Research Activity |
In the future, the construction of potential energy surfaces (PES) using neural network potential (NNP) will be continued and improved. From this PES, the adsorption potential energy for different chemical potentials of H2 will be obtained. Furthermore, quantum effects such as tunneling and zero-point energies will be incorporated to derive a complete picture of hydrogen adsorption in nanostructures.
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Report
(4 results)
Research Products
(10 results)
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[Presentation] Psi-k Conference2022
Author(s)
E. F. Arguelles, K. Shimizu
Organizer
Anisotropic Transport through a Diatomic Molecule Trapped in a Nanojunction
Related Report
Int'l Joint Research
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