title: Calculation Evidence of Staged Mott and Peierls Transitions in VO2 Revealed by Mapping Reduced-Dimension Potential Energy Surface.
abstract: Unraveling the metal-insulator transition (MIT) mechanism of VO2 becomes tremendously important for understanding strongly correlated character and developing switching applications of VO2. First-principles calculations were employed in this work to map the reduced-dimension potential energy surface of the MIT of VO2. In the beginning stage of MIT, a significant orbital switching between σ-type d(z(2)) and π-type d(x(2)-y(2))/d(yz) accompanied by a large V-V dimerization and a slight twisting angle change opens a band gap of ∼0.2 eV, which can be attributed to the electron-correlation-driven Mott transition. After that, the twisting angle of one chain quickly increases, which is accompanied by the appearance of a larger change in band gap from 0.2 to 0.8 eV, even though orbital occupancy is maintained. This finding can be ascribed to the structure-driven Peierls transition. The present study reveals that a staged electron-correlation-driven Mott transition and structure-driven Peierls transition are involved in MIT of VO2.
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , 1295 Dingxi Road, Shanghai 200050, China.|School of Materials Science and Engineering, Shanghai University , 99 Shangda Road, Shanghai 200444, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Chen
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , 1295 Dingxi Road, Shanghai 200050, China.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , 1295 Dingxi Road, Shanghai 200050, China.|School of Materials Science and Engineering, Shanghai University , 99 Shangda Road, Shanghai 200444, China.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Luo
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences , 1295 Dingxi Road, Shanghai 200050, China.|School of Materials Science and Engineering, Shanghai University , 99 Shangda Road, Shanghai 200444, China.
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Gao
keywords: Mott transition; Peierls transition; VO2(R/M1); first-principles calculations; potential energy surface