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Nanoscale physics -- Transitioning from DFT to DFT+Machine learning

ORAL · Invited

Abstract

Density functional theory (DFT) has been a powerful tool for computational quantum physics of materials and nanostructures while conventional classical potentials have been the primary way to undertake calculations beyond DFT’s computational reach for properties in which the role of electrons is passive (energetically preferred atomic arrangements, structure evolution, including rebonding, and mechanical properties, vibrational properties, and properties mediated by vibrations, e.g., lattice thermal conductivities). This talk will cover examples that highlight how the advent of machine-learning potentials (MLPs) is changing the computational landscape for such properties as we transition to DFT+MLPs. Examples include the structure and mechanical properties, including crack propagation, of amorphous graphene and BN monolayers, where in the latter case DFT+MLPs overturn results obtained using best-of-breed classical potentials. Other examples demonstrate new strides in handling systems that are beyond DFT’s reach, namely phonons and phonon-derived properties of complex nanostructures that were recently investigated jointly with vibrational electron-energy-loss spectroscopy (vEELS) by collaborators1 [vEELS in scanning transmission electron microscopes (STEM) recently achieved meV-scale energy resolution, opening up vibrational spectroscopy with atomic-scale resolution]. These systems include phonon vortices at heavy impurities in graphene, phonons of ferroelectric vortices in SrTiO3/PbTiO3 superlattices, the evolution of interfacial vibrational modes in (SrTiO3)n(CaTiO3)n superlattices (n=1 to n=27) and its impact on lattice thermal conductivities, the discovery of a crystalline material with record low thermal conductivity. and the nature of the hydrogen-bond network of water confined in carbon nanotubes.

[1] Jordan A. Hachtel, Oak Ridge National Laboratory, and Wu Zhou, University of the Chinese Academy of Sciences, Beijing, and members of their groups. Theory participants will be acknowledged during the talk

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Publication: 1. E. R. Hoglund, D.-L. Bao, A. O'Hara, S. Makarem, Z. T. Piontkowski, J. R. Matson, A. K. Yadav, R. C. Haislmaier, R. Engel-Herbert, J. F. Ihlefeld, J. Ravichandran, R. Ramesh, J. D. Caldwell, T. E. Beechem, J. A. Tomlo, J. A. Hachtel, S.T. Pantelides, P. E. Hopkins, J. M. Howe, "Emergent interface vibrational structure of oxide superlattices", Nature 601, 556 (2022).<br>2. E. Hoglund, D.-L. Bao, A. O'Hara, T. Pfeifer, Md S. B. Hoque, S. Makarem, J. M. Howe, S. T. Pantelides, P. E. Hopkins, and J. A. Hatchel, "Direct visualization of localized vibrations at complex grain boundaries", Advanced Materials 35, 2208920 (2023).<br>3. M. Xu, D.-L. Bao, A. Li, M. Gao, D. Meng, A. Li, S. Du, G. Su, S. J. Pennycook, S. T. Pantelides, and W. Zhou, "Single-atom vibrational spectroscopy with chemical-bonding sensitivity", Nature Materials 22, 612-618 (2023).<br>4. X. Zhang, Y.-T. Zhang, Y.-P. Wang, S. Li, S. Du, Y.-Y. Zhang, S. T. Pantelides, "Structure and mechanical properties of monolayer amorphous carbon and boron nitride", Physical Review B 109, 174106 (2024).<br>5. D-L. Bao, M. Xu, A-W. Li, G. Su, W. Zhou, S. T. Pantelides, "Phonon vortices at heavy impuri-ties in two-dimensional materials", Nanoscale Horizons 9, 248-253 (2024).<br>6. X. Xu, X. Jin, M. Kuehne, D-L. Bao, H. A. Walker, J. Martis, Y-M. Tu, C. L. Ritt, J. C. Idrobo, M. S. Strano, A. Majumdar, S. T. Pantelides, J. A. Hachtel, "Hydrogen bonding in water under extreme confinement unveiled by nanoscale vibrational spectroscopy and simulations." Under review at Na-ture. <br>6. E. R. Hoglund, H. A. Walker, Md. K. Hussain, D.-L. Bao, H. Ni, A. Mamun, J. Baxter, J. D. Caldwell, A. Khan, S. T. Pantelides, P. E. Hopkins, J. A. Hachtel, "Non-equivalent atomic vibra-tions at interfaces in a polar superlattice", Advanced Materials, 2402925 (2024).<br>7. Md S. B. Hoque, E. R. Hoglund, B. Zhao, D-L Bao, H. Zhou, S. Thakur, E. Osei-Agyemang, E. A. Scott, M. Surendran, J. A. Tomko, J. T. Gaskins, K. Aryana, S. Makarem, G. Balasubramanian,, A. Giri, T. Feng, J. A. Hachtel, J. Ravichandran, S. T. Pantelides, P. E. Hopkins, "Ruddles-den-Popper chalcogenides push the limit of mechanical stiffness and glass-like thermal conductivity in crystals." Under review at Nature Communications

Presenters

  • Sokrates T Pantelides

    Vanderbilt University, Department of Physics and Astronomy, Vanderbilt University

Authors

  • Sokrates T Pantelides

    Vanderbilt University, Department of Physics and Astronomy, Vanderbilt University