Stochastic many-body calculations of moiréstates in twisted bilayer graphene at high pressures  

作　　者：Mariya Romanova Vojtěch Vlček 

机构地区：[1]Department of Chemistry and Biochemistry,University of California,Santa Barbara,CA,93106-9510,USA

出　　处：《npj Computational Materials》2022年第1期89-98,共10页计算材料学（英文）

基　　金：The development of the off-diagonal self-energy and s-cRPA(VV)was supported by the NSF through NSF CAREER award Grant No.DMR-1945098;The development of the downfolding and the implementation(M.R.)were supported by the Materials Research Science and Engineering Centers(MRSEC)Program through Grant No.DMR-1720256(Seed Program);M.R.’s work was also supported by the NSF Quantum Foundry through Q-AMASE-i program Award No.DMR-1906325;The calculations were performed as part of the XSEDE123 computational Project No.TG-CHE180051;Use was made of computational facilities purchased with funds from the National Science Foundation(CNS-1725797)and administered by the Center for Scientific Computing(CSC).The CSC is supported by the California NanoSystems Institute and the Materials Research Science and Engineering Center(MRSEC,NSF DMR-1720256)at UC Santa Barbara.

摘　　要：We introduce three developments within the stochastic many-body perturbation theory:efficient evaluation of off-diagonal self-energy terms,construction of Dyson orbitals,and stochastic constrained random phase approximation.The stochastic approaches readily handle systems with thousands of atoms.We use them to explore the electronic states of twisted bilayer graphene(tBLG)characterized by giant unit cells and correlated electronic states.We document the formation of electron localization under compression;weakly correlated states are merely shifted in energy.We demonstrate how to efficiently downfold the correlated subspace on a model Hamiltonian with a screened frequency-dependent two-body interaction.For the 6°tBLG system,the onsite interactions are between 200 and 300 meV under compression.The Dyson orbitals exhibit spatial distribution similar to the mean-field single-particle states.Under pressure,the electron-electron interactions increase in the localized states;however,the dynamical screening does not fully balance the dominant bare Coulomb interaction.

关 键 词：INTERACTION TWISTED STOCHASTIC 

分 类 号：O57[理学—粒子物理与原子核物理]