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We provide a systematic real space derivation of the continuum Hamiltonian for a graphene bilayer starting from a microscopic lattice theory, allowing for an arbitrary inhomogeneous smooth lattice deformation, including a twist. Two…

Strongly Correlated Electrons · Physics 2023-02-24 Oskar Vafek , Jian Kang

We provide a formal derivation of a reduced model for twisted bilayer graphene (TBG) from Density Functional Theory. Our derivation is based on a variational approximation of the TBG Kohn-Sham Hamiltonian and asymptotic limit techniques. In…

Mesoscale and Nanoscale Physics · Physics 2023-04-14 Eric Cancès , Louis Garrigue , David Gontier

We construct an analytic continuum model to describe the electronic structure and the electron-phonon interaction in twisted bilayer graphenes with arbitrary lattice deformation. Starting from the tight-binding model, we derive the…

Mesoscale and Nanoscale Physics · Physics 2020-05-20 Mikito Koshino , Nguyen N. T. Nam

We provide a method for the generation of effective continuum Hamiltonians that goes beyond the well known k.p method in being equally effective in both high, and low (or no) symmetry situations. Our approach is based on a surprising exact…

Mesoscale and Nanoscale Physics · Physics 2019-07-10 N. Ray , F. Rost , D. Weckbecker , M. Vogl , S. Sharma , R. Gupta , O. Pankratov , S. Shallcross

We analyze a description of twisted graphene bilayers, that incorporates deformation of the layers due to the nature modern interlayer potentials, and a modification of the hopping parameters between layers in the light of the classic…

Strongly Correlated Electrons · Physics 2019-05-29 Francisco Guinea , Niels R. Walet

In this paper, we extend the discrete-to-continuum procedure we developed in our previous work to derive a continuum variational model for a hexagonal twisted bilayer material in which one layer is fixed. We use a discrete energy containing…

Materials Science · Physics 2023-02-15 Malena I. Espanol , Dmitry Golovaty , J. Patrick Wilber

We demonstrate that there exists a continuum Hamiltonian $H(\bf{r},\bf{p})$ that is formally the operator equivalent of the general tight-binding method, inheriting the associativity and Hermiticity of the latter operator. This provides a…

Materials Science · Physics 2019-01-16 F. Rost , R. Gupta , M. Fleischmann , D. Weckbecker , N. Ray , J. Olivares , M. Vogl , S. Sharma , O. Pankratov , S. Shallcross

We introduce a complete physical model for the single-particle electronic structure of twisted bilayer graphene (tBLG), which incorporates the crucial role of lattice relaxation. Our model, based on $k \cdot p$ perturbation theory, combines…

Mesoscale and Nanoscale Physics · Physics 2019-08-14 Stephen Carr , Shiang Fang , Ziyan Zhu , Efthimios Kaxiras

We introduce a minimum tight-binding model with only three parameters extracted from graphene and untwisted bilayer graphene. This model reproduces quantitatively the electronic structure of not only these two systems and bulk graphite near…

Mesoscale and Nanoscale Physics · Physics 2018-09-12 Xianqing Lin , David Tománek

Using the method developed in the companion paper, we construct the effective continuum theories for two different microscopic tight binding models of the twisted bilayer graphene at the twist angle of $1.05^\circ$, one Slater-Koster based…

Strongly Correlated Electrons · Physics 2023-02-24 Jian Kang , Oskar Vafek

We consider the problem of numerically computing the quantum dynamics of an electron in twisted bilayer graphene. The challenge is that atomic-scale models of the dynamics are aperiodic for generic twist angles because of the…

Mathematical Physics · Physics 2024-02-27 Tianyu Kong , Diyi Liu , Mitchell Luskin , Alexander B. Watson

We generalize the continuum model for Moir\'e structures made from twisted graphene layers, in order to include lattice relaxation and the formation of channels at very small (marginal) twist angles. We show that a precise description of…

Strongly Correlated Electrons · Physics 2020-02-19 Niels R. Walet , Francisco Guinea

We present efficient angle-dependent low-energy Hamiltonians to describe the properties of the twisted bilayer graphene (tBLG) heterostructure, based on {\it ab initio} calculations of mechanical relxation and electronic structure. The…

Mesoscale and Nanoscale Physics · Physics 2019-08-02 Shiang Fang , Stephen Carr , Ziyan Zhu , Daniel Massatt , Efthimios Kaxiras

We consider the instability of bilayer graphene with respect to a distorted configuration in the same spirit as the model introduced by Su, Schrieffer and Heeger. By computing the total energy of a distorted bilayer, we conclude that the…

Mesoscale and Nanoscale Physics · Physics 2009-02-12 Vitor M. Pereira , R. M. Ribeiro , N. M. R. Peres , A. H. Castro Neto

The low energy excitations of graphene can be described by a massless Dirac equation in two spacial dimensions. Curved graphene is proposed to be described by coupling the Dirac equation to the corresponding curved space. This covariant…

Strongly Correlated Electrons · Physics 2009-11-13 Maria A. H. Vozmediano , Fernando de Juan , Alberto Cortijo

Starting from the effective Hamiltonian arising from the tight binding model, we study the behaviour of low-lying excitations for bilayer graphene placed in periodic external magnetic fields by using irreducible second order supersymmetry…

Mesoscale and Nanoscale Physics · Physics 2024-08-06 David J. Fernández C. , O. Pavón-Torres

The first-order continuum PDE model proposed by Bistritzer and MacDonald in \cite{bistritzer2011moire} accurately describes the single-particle electronic properties of twisted bilayer graphene (TBG) at small twist angles. In this paper, we…

Mathematical Physics · Physics 2025-02-27 Solomon Quinn , Tianyu Kong , Mitchell Luskin , Alexander B. Watson

We show that the physics of deformation in $\alpha$-, $\beta$-, and $6,6,12$-graphyne is, despite their significantly more complex lattice structures, remarkably close to that of graphene, with inhomogeneously strained graphyne described at…

Materials Science · Physics 2019-08-28 R. Gupta , S. Maisel , F. Rost , D. Weckbecker , M. Fleischmann , H. Soni , S. Sharma , A. Görling , S. Shallcross

We present simple models to describe the in-plane and the out-of-plane lattice relaxation in twisted bilayer and symmetrically twisted trilayer graphene. Analytical results and series expansions show that for twist angles {\theta} > 1…

Mesoscale and Nanoscale Physics · Physics 2023-11-28 Adrián Ceferino , Francisco Guinea

We use a symmetry approach to construct a systematic derivative expansion of the low energy effective Hamiltonian modifying the continuum Dirac description of graphene in the presence of non-uniform elastic deformations. We extract all…

Mesoscale and Nanoscale Physics · Physics 2015-05-26 Juan L. Mañes , Fernando de Juan , Mauricio Sturla , María A. H. Vozmediano
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