Moiré-pattern interlayer potentials in van der Waals materials in the random-phase approximation

Leconte, Nicolás; Jung, Jeil; Lebègue, Sébastien; Gould, Tim

doi:10.1103/physrevb.96.195431

Cited by 32 publications

(39 citation statements)

References 80 publications

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“…Despite having a minimum as a function of distance between the two centres, this arrangement is unstable as the dimers wish to slide apart sideways (see later discussion on Fig. 3 ) to reduce electrostatic effects, such as overlap of the densities of the monomers and static quadrupole–quadropole interactions, which make metastable AA graphite ≈0.23 kcal/mol/C less energetically favourable compared to AB graphite [ 75 ]. This configuration thus involves competition between dispersion forces, repulsive electrostatic forces, and other exchange and correlation effects, making it a good test of dispersion corrections.…”

Section: Resultsmentioning

confidence: 99%

Are dispersion corrections accurate outside equilibrium? A case study on benzene

Gould¹,

Johnson²,

Tawfik³

2018

Beilstein J. Org. Chem.

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Modern approaches to modelling dispersion forces are becoming increasingly accurate, and can predict accurate binding distances and energies. However, it is possible that these successes reflect a fortuitous cancellation of errors at equilibrium. Thus, in this work we investigate whether a selection of modern dispersion methods agree with benchmark calculations across several potential-energy curves of the benzene dimer to determine if they are capable of describing forces and energies outside equilibrium. We find the exchange-hole dipole moment (XDM) model describes most cases with the highest overall agreement with reference data for energies and forces, with many-body dispersion (MBD) and its fractionally ionic (FI) variant performing essentially as well. Popular approaches, such as Grimme-D and van der Waals density functional approximations (vdW-DFAs) underperform on our tests. The meta-GGA M06-L is surprisingly good for a method without explicit dispersion corrections. Some problems with SCAN+rVV10 are uncovered and briefly discussed.

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Section: Resultsmentioning

confidence: 99%

Are dispersion corrections accurate outside equilibrium? A case study on benzene

Gould¹,

Johnson²,

Tawfik³

2018

Beilstein J. Org. Chem.

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“…We performed the band structure calculation using a tight-binding model informed from ab initio density functional theory (DFT) calculations for the atomic and electronic structures. The atomic structure includes the relaxation effects through LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) molecular dynamic simulations ( 60 ) using force fields parameterized to fit the random phase approximation total energy data (EXX + RPA) for different local stacking configurations of BG ( 61 – 63 ). Our Kagome-like moiré is built from a superposition of two moiré patterns, one from the BG/BG interface and another from BG/hBN, which are commensurately superposed and whose bands can be folded into a small superstructure Brillouin zone.…”

Section: Methodsmentioning

confidence: 99%

Ultrahigh-resolution scanning microwave impedance microscopy of moiré lattices and superstructures

et al. 2020

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Two-dimensional heterostructures composed of layers with slightly different lattice vectors exhibit new periodic structure known as moiré lattices, which, in turn, can support novel correlated and topological phenomena. Moreover, moiré superstructures can emerge from multiple misaligned moiré lattices or inhomogeneous strain distributions, offering additional degrees of freedom in tailoring electronic structure. High-resolution imaging of the moiré lattices and superstructures is critical for understanding the emerging physics. Here, we report the imaging of moiré lattices and superstructures in graphene-based samples under ambient conditions using an ultrahigh-resolution implementation of scanning microwave impedance microscopy. Although the probe tip has a gross radius of ~100 nm, spatial resolution better than 5 nm is achieved, which allows direct visualization of the structural details in moiré lattices and the composite super-moiré. We also demonstrate artificial synthesis of novel superstructures, including the Kagome moiré arising from the interplay between different layers.

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“…Using Eqs. (6-7) at zero pressure and using the EXX+RPA equilibrium distances for each stacking 52 we…”

Section: Model Hamiltonian For Twisted Bi-bilayer Graphenementioning

confidence: 99%

Flat bands in twisted double bilayer graphene

2019

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Flatbands with extremely narrow bandwidths on the order of a few mili-electron volts can appear in twisted multilayer graphene systems for appropriate system parameters. Here we investigate the electronic structure of a twisted bi-bilayer graphene, or twisted double bilayer graphene, to find the parameter space where isolated flatbands can emerge as a function of twist angle, vertical pressure, and interlayer potential differences. We find that in twisted bi-bilayer graphene the bandwidth is generally flatter than in twisted bilayer graphene by roughly up to a factor of two in the same parameter space of twist angle θ and interlayer coupling ω, making it in principle simpler to tailor narrow bandwidth flatbands. Application of vertical pressure can enhance the first magic angle in minimal models at θ ∼ 1.05 • to larger values of up to θ ∼ 1.5 • when P ∼ 2.5 GPa, where θ ∝ ω/υF . Narrow bandwidths are expected in bi-bilayers for a continuous range of small twist angles, i.e. without magic angles, when intrinsic bilayer gaps open by electric fields, or due to remote hopping terms. We find that moderate vertical electric fields can contribute in lifting the degeneracy of the low energy flatbands by enhancing the primary gap near the Dirac point and the secondary gap with the higher energy bands. Distinct valley Chern bands are expected near 0 • or 180 • alignments.

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Moiré-pattern interlayer potentials in van der Waals materials in the random-phase approximation

Cited by 32 publications

References 80 publications

Are dispersion corrections accurate outside equilibrium? A case study on benzene

Are dispersion corrections accurate outside equilibrium? A case study on benzene

Ultrahigh-resolution scanning microwave impedance microscopy of moiré lattices and superstructures

Flat bands in twisted double bilayer graphene

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