Interacting models for twisted bilayer graphene: a quantum chemistry approach

• DOI: 10.48550/arxiv.2211.09243
• Publication Date: 2022-01-01
• Authors: Fabian M. Faulstich; Kevin D. Stubbs; Qinyi Zhu; Tomohiro Soejima; Rohit Dilip; Huan-Chen Zhai; Raehyun Kim; Michael P. Zaletel; Garnet Kin‐Lic Chan; Lin Lin
• Keywords: Anyon

The nature of correlated states in twisted bilayer graphene (TBG) at the magic angle has received intense attention recent years. We present a numerical study an interacting Bistritzer-MacDonald (IBM) model TBG using suite methods quantum chemistry, including Hartree-Fock, coupled cluster singles, doubles (CCSD), and perturbative triples (CCSD(T)), as well chemistry formulation density matrix renormalization group method (DMRG). Our treatment is agnostic to gauge choices, hence we new gauge-invariant detect spontaneous symmetry breaking models. To benchmark our approach, focus on simplified spinless, valleyless IBM model. At integer filling ($ν=0$), all agree terms energy $C_{2z} \mathcal{T}$ breaking. Additionally, part benchmarking, explore impact different schemes for removing ``double-counting'' results suggest that cross-validation models may be needed future studies system. After benchmarking approach filling, perform first systematic near (for $|ν|< 0.2$). In this regime, find ground state can metallic phase. appears have low entropy, therefore relatively approximated by single Slater determinant. Furthermore, observe many entropy with energies very close regime.