Möbius and twisted graphene nanoribbons: Stability, geometry, and electronic properties

Abstract

Results of classical force field geometry optimizations for twisted graphene nanoribbons with a number of twists N(t) varying from 0 to 7 (the case N(t)=1 corresponds to a half-twist Möbius nanoribbon) are presented in this work. Their structural stability was investigated using the Brenner reactive force field. The best classical molecular geometries were used as input for semiempirical calculations, from which the electronic properties (energy levels, HOMO, LUMO orbitals) were computed for each structure. CI wavefunctions were also calculated in the complete active space framework taking into account eigenstates from HOMO-4 to LUMO+4, as well as the oscillator strengths corresponding to the first optical transitions in the UV-VIS range. The lowest energy molecules were found less symmetric than initial configurations, and the HOMO-LUMO energy gaps are larger than the value found for the nanographene used to build them due to electronic localization effects created by the twisting. A high number of twists leads to a sharp increase of the HOMO-->LUMO transition energy. We suggest that some twisted nanoribbons could form crystals stabilized by dipolar interactions.

Super flexibility and stability of graphene nanoribbons under severe twist

“…[16][17][18] Supported GNRs can have even more abrupt distortions, such as loops and folds, because of the support interactions. [23][24][25] Even carbon nanotubes can be fabricated by twisting GNRs. 22 The geometry and electronic properties of the twist GNRs have been intensively studied because they have high claims for usage as sensors, spintronic devices and ballistic transistors.…”

Electron-electron interactions and topology in the electronic properties of gated graphene nanoribbon rings in Möbius and cylindrical configurations

“…10 Interestingly, it has been suggested that nontrivial properties of graphene nanoribbons can be generated directly by engineering a nontrivial Möbius geometry of the nanoribbon without the need for the spin-orbit coupling. [40][41][42][43][44][45][46][47][48][49][50][51] For example, it was shown by Guo et al 46 that one electron states of a class of Möbius graphene ribbons with zigzag edges can be understood by introducing a non-Abelian gauge field 46 as in topological insulators. [6][7][8][9][10][11][12] However, these authors used the s orbitals instead of p z orbitals as the basis needed to describe graphene nanoribbons and limited their work to an even number of atomic chains.…”

Zero Landau Level in Folded Graphene Nanoribbons

“…Curled and folded edges might be much more ubiquitous than previously assumed [3,4]. Their fascinating electrostatic [4,5] and electronic properties [6,7], and the possibilities afforded by the third dimension, are rapidly making folded structures a very active graphene research subfield. Folds under a uniform and perpendicular magnetic field are an ideal system to study effectively non-homogeneous magnetic fields, since the flux through the nanoribbon changes sign across the fold.…”